Apparatus for scanning sites on a wafer along a short dimension of the sites

ABSTRACT

An exposure apparatus ( 210 ) for transferring a mask pattern ( 346 ) from a mask ( 212 ) to a substrate ( 214 ) includes a first site ( 315 ) having a first site dimension ( 348 ) along a first axis and a second site dimension ( 350 ) along a second axis that is perpendicular to the first axis. The second site dimension ( 350 ) is larger than the first site dimension ( 348 ). The exposure apparatus ( 210 ) includes an illumination system ( 218 ), a mask stage assembly ( 222 ), a substrate stage assembly ( 224 ), and a control system ( 228 ). The illumination system ( 218 ) generates an illumination beam ( 235 ) that is directed at the mask ( 212 ). The mask stage assembly ( 222 ) retains and positions the mask ( 212 ) along the first axis relative to the illumination beam ( 235 ). The substrate stage assembly ( 224 ) retains and positions the substrate ( 214 ) along the first axis. The control system ( 228 ) controls the illumination system ( 218 ), the mask stage assembly ( 222 ), and the substrate stage assembly ( 224 ) so that a portion of the mask pattern ( 346 ) is transferred to a portion of the first site ( 315 ) while the mask stage assembly ( 222 ) is moving the mask ( 212 ) along the first axis, and the substrate stage assembly ( 224 ) is moving the substrate ( 214 ) along the first axis.

RELATED APPLICATIONS

This application claims priority on U.S. Provisional Application Ser.No. 61/060,411, filed Jun. 10, 2008 and entitled “SYSTEM ARCHITECTUREFOR ACHIEVING HIGHER SCANNER THROUGHPUT”; on U.S. ProvisionalApplication Ser. No. 61/078,251, filed Jul. 3, 2008 and entitled “HIGHNA CATADIOPTRIC PROJECTION OPTICS FOR IMAGING TWO RETICLES ONTO ONEWAFER”; on U.S. Provisional Application Ser. No. 61/078,254 filed onJul. 3, 2008 and entitled “X-SCANNING EXPOSURE SYSTEM WITH CONTINUOUSEXPOSURE”; and on U.S. Provisional Application Ser. No. 61/104,477 filedon Oct. 10, 2008. As far as is permitted, the contents of U.S.Provisional Application Ser. Nos. 61/060,411, 61/078,251, 61/078,254 and61/104,477 are incorporated herein by reference.

BACKGROUND

Exposure apparatuses for semiconductor processing are commonly used totransfer images from a reticle onto a semiconductor wafer duringsemiconductor processing. A typical exposure apparatus includes anillumination source, a reticle stage assembly that positions a reticle,a projection optical assembly, and a wafer stage assembly that positionsa semiconductor wafer.

As illustrated in prior art FIG. 1A, each wafer 1P is typically dividedinto a plurality of rectangular shaped integrated circuits 2P (sometimesreferred to as “sites”). Further, each site 2P has a first sitedimension 3P along a first axis (e.g. the X axis), and a second sitedimension 4P along a second axis (e.g. the Y axis). Typically, thesecond site dimension 4P is greater than the first site dimension 3P.For example, a common site 2P has a first site dimension 3P oftwenty-six millimeters and a second site dimension 4P of thirty-threemillimeters.

There are two kinds of exposure apparatuses that are generally known andcurrently used. The first kind is commonly referred to as a Stepperlithography system. In a Stepper lithography system, the reticle isfixed (except for slight corrections in position) and the wafer stageassembly moves the wafer to fixed chip sites where the illuminationsource directs an illumination beam at an entire reticle pattern on thereticle. This causes the entire reticle pattern to be exposed onto oneof the chip sites of the wafer at one time. At the time of exposure, thereticle and the wafer are stationary. After the exposure, the wafer ismoved (“stepped”) to the next site for subsequent exposure.

The second kind of system is commonly referred to as a Scannerlithography system. In a Scanner lithography system, the reticle stageassembly moves the reticle in one direction along a scan axis 5P (thesecond axis) concurrently with the wafer stage assembly moving the waferin one direction along the scan axis 5P during the exposure of a firstsite 1S. With this system, the illumination beam is slit shaped andilluminates only a portion of the reticle pattern on the reticle. Thiscauses a slit shaped pattern beam 6P to be imaged onto the wafer 1P.This pattern beam 6P exposes only a portion of the first site 1S at agiven moment, and the entire reticle pattern is exposed and transferredto the first site 1S over time as the reticle pattern is moved relativeto the illumination beam. After exposure of the first site 1S, the wafer1P is stepped along a step axis 7P (the first axis) and subsequently asecond site 2S is scanned while moving the wafer 1P in the oppositedirection along the scan axis 5P. With this design, each site 1S, 2S isscanned along the second axis (the longer dimension of the site).

In FIG. 1A, dashed line 11P illustrates an exposure pattern 11P of thefirst row of sites 2P on the wafer 1P. The exposure pattern 11Pcomprises a plurality of scanning operations 13P and a plurality ofstepping operations 15P, wherein the scanning operations 13P and thestepping operations 15P alternate so that the exposure proceeds in ascan-step-scan-step-scan fashion. As illustrated, and as noted above,the scanning of each site 2P occurs across the second site dimension 4Pand the steps between each site 2P occurs along the first axis. Thistypically results in scanning times and stepping times that are nearlyequal to each other.

The throughput capacity of an exposure apparatus used in lithography isoften quoted in the number of wafers that can be printed per hour (WPH).Throughput depends on many factors, such as the reticle stage and waferstage performances, nozzle capabilities (for immersion type exposureapparatuses), and available power for the illumination system.

Additionally, the optical assembly is one of the limiting factors in theperformance of a lithography system. More specifically, the opticalassembly is thought of as limiting the performance in terms of theresolution, or smallest printable feature. One design tradeoff that isutilized includes keeping a used field of the optical assembly as smallas possible to minimize aberrations. For example, FIG. 1B illustrates afield of view 17P (illustrated with a dashed circle) for a prior artoptical assembly having a numerical aperture (NA) of 1.30. In thisexample, the field of view 17P defines a substantially rectangular usedfield 19P. In the example provided above, to expose a site that istwenty-six millimeters by thirty-three millimeters, the used field 19Phas a first field dimension 21P of about twenty-six millimeters alongthe first axis, and a second field dimension 23P of about fivemillimeters along the second axis. These measurements are specified atthe wafer plane. The corresponding dimensions at the reticle plane aredetermined by the magnification ratio of the projection opticalassembly. For example, in a 4× reduction machine, the reticle dimensionsare 4× bigger.

Additionally, in order to further minimize or correct aberrations atsuch a high NA, the optical assembly is catadioptric. This requires theused field 19P to be off-axis in order to avoid obscurations from therelative surfaces. In one prior art design, the closest edge of the usedfield 19P has an offset distance 25P of about 2.5 millimeters from anoptical axis 27P. This means the diagonal of the point in the used field19P farthest from the optical axis 27P is 15.01 millimeters, and thefield of view 17P has a field diameter of 30.02 millimeters, asexplained in Equation 1.

2*√{square root over (13 ²+(5+2.5)²)}=30.02 mm   (Equation 1)

Using the specifications for one embodiment of a prior system, wherethere are 125 chips per wafer, each chip is 16×32 mm, average waferstage acceleration of 2.5G in the X axis and the Y axis, an averagereticle stage acceleration of 10G, and a wafer stage scan velocity of0.7 m/s, the maximum possible throughput is 246 WPH (assuming nooverhead time between wafers).

As is known, there is a never ending search to increase the throughputin exposure apparatuses.

SUMMARY

The present invention is directed to an exposure apparatus fortransferring a first mask pattern from a first mask to a substrate. Thesubstrate includes a first site having a first site dimension along afirst axis and a second site dimension along a second axis that isperpendicular to the first axis. The second site dimension is largerthan the first site dimension.

In one embodiment, the exposure apparatus includes an illuminationsystem, a first mask stage assembly, a substrate stage assembly, and acontrol system. The illumination system generates a first illuminationbeam that is directed at the first mask. The first mask stage assemblyretains and positions the first mask along the first axis relative tothe first illumination beam. The substrate stage assembly retains andpositions the substrate along the first axis. The control systemcontrols the illumination system, the first mask stage assembly and thesubstrate stage assembly so that a portion of the first mask pattern istransferred to a portion of the first site while the first mask stageassembly is moving the first mask along the first axis, and thesubstrate stage assembly is moving the substrate along the first axis.

With this design, one or more of the sites of the substrate are scannedalong their short dimension. As a result thereof, the throughput of theexposure apparatus can be improved.

In certain embodiments, the first illumination beam illuminates thefirst mask pattern to generate a first pattern beam. In this embodiment,the exposure apparatus further comprises an optical assembly thatfocuses the first pattern beam on the substrate. Additionally, theoptical assembly includes a used field having a first field dimensionalong the first axis and a second field dimension along the second axis,wherein the first field dimension is smaller than the second fielddimension. In one such embodiment, the second field dimension is betweenapproximately thirty millimeters and thirty-five millimeters. Further,in this embodiment, the first field dimension can be betweenapproximately 1.5 mm and 5 mm. Still further, in one embodiment, thefirst field dimension is shorter than the first site dimension and thesecond field dimension is equal to or greater than the second sitedimension. As provided herein, the design of the optical assemblyprovided herein allows for the scanning of the sites along their shortdimension.

In one embodiment, the exposure apparatus further comprises a secondmask stage assembly that retains and positions a second mask. In thisembodiment, the illumination system generates a second illumination beamthat is directed at the second mask. Additionally, the secondillumination beam illuminates a second mask pattern of the second maskto generate a second pattern beam. Further, in this embodiment, theoptical assembly focuses the first pattern beam and the second patternbeam on the substrate.

In some embodiments, the substrate may further include a second site,and the control system may control the illumination system, the maskstage assemblies and the substrate stage assembly to transfer an imageof the first mask pattern to the first site, and an image of the secondmask pattern to the second site. In one such embodiment, the controlsystem controls the substrate stage assembly to continuously move thesubstrate at a constant velocity along the first axis when transferringthe images to the first site and the second site. With this design,multiple sites can be exposed between stepping of the substrate. Thisimproves the throughput of the exposure apparatus.

The present invention is further directed to a method for transferring afirst mask pattern from a first mask to a substrate, a method for makingan exposure apparatus, and a method of manufacturing a wafer with theexposure apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of this invention, as well as the invention itself,both as to its structure and its operation, will be best understood fromthe accompanying drawings, taken in conjunction with the accompanyingdescription, in which similar reference characters refer to similarparts, and in which:

FIG. 1A is a simplified illustration of a prior art exposure pattern ona wafer;

FIG. 1B is a simplified illustration of a field of view for a prior artoptical assembly;

FIG. 2 is a schematic illustration of a first embodiment of an exposureapparatus having features of the present invention;

FIG. 3A is a simplified top illustration of a substrate and an exposurepattern having features of the present invention;

FIG. 3B is a simplified top illustration of a field of view for anoptical assembly having features of the present invention;

FIG. 3C is a simplified top illustration of the mask and a portion ofthe substrate at the beginning of a scanning procedure on a first site;

FIG. 3D is a simplified top illustration of the mask and a portion ofthe substrate at the end the scanning procedure on the first site;

FIG. 3E is a simplified top illustration of the mask and a portion ofthe substrate at the beginning of a scanning procedure on a second site;

FIG. 3F is a simplified illustration of an optical assembly havingfeatures of the present invention;

FIG. 4 is a schematic illustration of a second embodiment of an exposureapparatus having features of the present invention;

FIG. 5A is a simplified top view of an embodiment of a substrate exposedby the exposure apparatus of FIG. 4;

FIG. 5B is a simplified illustration of a field of view of an embodimentof an optical assembly having features of the present invention;

FIG. 6A is a simplified side view of a first mask, a second mask, anoptical assembly, and a substrate at a beginning of an exposure of afirst site;

FIG. 6B is a simplified side view of the first mask, the second mask,the optical assembly, and the substrate at a beginning of an exposure ofa second site;

FIG. 6C is a simplified side view of the first mask, the second mask,the optical assembly, and the substrate at a beginning of an exposure ofa third site;

FIG. 6D is a simplified side view of the first mask, the second mask,the optical assembly, and the substrate at a beginning of an exposure ofa fourth site;

FIGS. 7A-7I illustrate one embodiment of the exposure of four sites;

FIGS. 8A-8I illustrate another embodiment of the exposure of four sites;

FIGS. 9A-98I illustrate yet another embodiment of the exposure of foursites;

FIGS. 10A-10D illustrate one embodiment of the exposure of one site;

FIGS. 11A-11D illustrate another embodiment of the exposure of one site;

FIG. 12 is a schematic illustration of the first mask, the second mask,the substrate, and an embodiment of an optical assembly having featuresof the present invention;

FIG. 13 is a simplified perspective view of portion of anotherembodiment of an exposure apparatus having features of the presentinvention;

FIG. 14 is a simplified top view of an embodiment of a substrate exposedutilizing the exposure apparatus illustrated in FIG. 13;

FIG. 15A is a flow chart that outlines a process for manufacturing adevice in accordance with the present invention; and

FIG. 15B is a flow chart that outlines device processing in more detail.

DESCRIPTION

FIG. 2 is a schematic illustration of a precision assembly, namely anexposure apparatus 210 that transfers features from a mask 212 to asubstrate 214 such as a semiconductor wafer that includes a plurality ofsites 315 (illustrated in FIG. 3A). The design of the exposure apparatus210 can be varied to achieve the desired throughput, and quality anddensity of the features on the substrate 214. In FIG. 2, the exposureapparatus 210 includes an apparatus frame 216, an illumination system218 (irradiation apparatus), a projection optical assembly 220, a maskstage assembly 222, a substrate stage assembly 224, a measurement system226, and a control system 228. Further, the exposure apparatus 210mounts to a mounting base 230, e.g., the ground, a base, or a floor, orsome other supporting structure.

As an overview, in certain embodiments, the projection optical assembly220 is designed to have a larger field of view 331 (illustrated in FIG.3B) and/or one or more of the sites 315 of the substrate 214 are scannedalong their short dimension. Further, in certain embodiments, theexposure apparatus 410 (illustrated in FIG. 4) is designed to usemultiple masks 412 to sequentially expose adjacent sites 315. Thesefeatures can increase the throughput capabilities of the exposureapparatuses 210, 410.

A number of Figures include an orientation system that illustrates an Xaxis, a Y axis that is orthogonal to the X axis, and a Z axis that isorthogonal to the X and Y axes. It should be noted that any of theseaxes can also be referred to as the first, second, and/or third axes.

The exposure apparatus 210 discussed herein is particularly useful as aphotolithography system for semiconductor manufacturing that transfersfeatures from a reticle (the mask 212) to a wafer (the substrate 214).However, the exposure apparatus 210 provided herein is not limited to aphotolithography system for semiconductor manufacturing. The exposureapparatus 210, for example, can be used as an LCD photolithographysystem that exposes a liquid crystal display device pattern onto a glassplate or a photolithography system for manufacturing a thin filmmagnetic head. Further, in certain embodiments, the concepts of thepresent invention can be utilized in a maskless exposure apparatus.

The apparatus frame 216 is rigid and supports the components of theexposure apparatus 210. The apparatus frame 216 illustrated in FIG. 2supports the mask stage assembly 222, the projection optical assembly220, the illumination system 218, and the substrate stage assembly 224above the mounting base 230.

The illumination system 218 includes an illumination source 232 and anillumination optical assembly 234. The illumination source 232 emits anillumination beam 235 (irradiation) of light energy. The illuminationoptical assembly 234 guides the illumination beam 235 from theillumination source 232 to near the mask 212. The illumination beam 235illuminates the mask 212 to generate a pattern beam 236 (e.g. imagesfrom the mask 212) that exposes the substrate 214. In one embodiment,the illumination beam 235 is generally slit shaped and illuminates onlya portion of the mask 212 at any given moment. Similarly, the patternbeam 236 is generally slit shaped and exposes only a portion of thesubstrate 214 at any given moment. In the embodiment illustrated in FIG.2, the mask stage assembly 222 moves the mask 212 back and forth alongthe first axis (e.g. the X axis) during scanning of the sites 315.

In FIG. 1, the mask 212 is at least partly transparent, and theillumination beam 235 is transmitted through a portion of the mask 212.Alternatively, the mask 212 can be reflective, and the illumination beam235 can be directed at the mask 212 and reflected off of the mask 212.

The illumination source 232 can be a g-line source (436 nm), an i-linesource (365 nm), a KrF excimer laser (248 nm), an ArF excimer laser (193nm) or an F₂ laser (157 nm). Alternatively, the illumination source 232can generate charged particle beams such as an x-ray or an electronbeam. For instance, in the case where an electron beam is used,thermionic emission type lanthanum hexaboride (LaB₆) or tantalum (Ta)can be used as a cathode for an electron gun.

The projection optical assembly 220 projects and/or focuses the patternbeam 236 from the mask 212 to the substrate 214. Depending upon thedesign of the exposure apparatus 210, the projection optical assembly220 can magnify or reduce the pattern beam 236. In one non-exclusiveembodiment, the projection optical assembly 220 reduces the pattern beam236 by a reduction factor of four. As a result thereof, during theexposure of a site 315, the mask stage assembly 222 must move the mask212 a distance that is four times greater than a distance in which thesubstrate stage assembly 224 moves the substrate 214. Stated in anotherfashion, if the projection optical assembly 220 has a reduction factorof 4, the substrate 214 is moved at a rate that is one fourth that ofthe mask 212.

In certain embodiments, as discussed in more detail below, theprojection optical assembly 220 includes a plurality of optical elements220A (illustrated in phantom in FIG. 2) that are designed and arrangedso that the projection optical assembly 220 will have a relatively largefield of view 331 so that one or more of the sites 315 of the substrate214 can be scanned along their short dimension. A discussion of possiblefields of view 331 for the projection optical assembly 220 is describedin more detail below.

The mask stage assembly 222 holds and positions the mask 212 relative tothe projection optical assembly 220 and the substrate 214. The maskstage assembly 222 can include (i) a mask stage 237 having a chuck (notshown) for holding the mask 212, and (ii) a mask stage mover assembly238 that moves and positions the mask stage 237 and the mask 212. Forexample, the mask stage mover assembly 238 can move the mask stage 237and the mask 212 along the Y axis, along the X axis, and about the Zaxis. Alternatively, for example, the mask stage mover assembly 238could be designed to move the mask stage 237 and the mask 212 with morethan three degrees of freedom, or less than three degrees of freedom.For example, the mask stage mover assembly 238 can include one or morelinear motors, rotary motors, planar motors, voice coil actuators, orother type of actuators. In the embodiment illustrated in FIG. 2, themask stage mover assembly 238 moves the mask 212 along the first axis(e.g. the X axis) during scanning of the sites 315.

Somewhat similarly, the substrate stage assembly 224 holds and positionsthe substrate 214 with respect to the pattern beam 236. The substratestage assembly 224 can include (i) a substrate stage 240 having a chuck(not shown) for holding the substrate 214, and (ii) a substrate stagemover assembly 242 that moves and positions the substrate stage 240 andthe substrate 214. For example, the substrate stage mover assembly 242can move the substrate stage 240 and the substrate 214 along the Y axis,along the X axis, and about the Z axis. Alternatively, for example, thesubstrate stage mover assembly 242 could be designed to move thesubstrate stage 240 and the substrate 214 with more than three degreesof freedom, or less than three degrees of freedom. For example, thesubstrate stage mover assembly 242 can include one or more linearmotors, rotary motors, planar motors, voice coil actuators, or othertype of actuators. In the embodiment illustrated in FIG. 2, thesubstrate stage mover assembly 242 moves the substrate 214 along thefirst axis (e.g. the X axis) during scanning of the sites 315 and movesthe substrate 214 along the second axis (e.g. the Y axis) while steppingin between scanning of the sites 315.

The measurement system 226 monitors movement of the mask 212 and thesubstrate 214 relative to the projection optical assembly 220 or someother reference. With this information, the control system 228 cancontrol the mask stage assembly 222 to precisely position the mask 212and the substrate stage assembly 224 to precisely position the substrate214. For example, the measurement system 226 can utilize multiple laserinterferometers, encoders, and/or other measuring devices.

The control system 228 is connected to the illumination system 218, themask stage assembly 222, the substrate stage assembly 224, and themeasurement system 226. The control system 228 receives information fromthe measurement system 226, and controls the illumination system 218 andthe stage assemblies 222, 224 to precisely position the mask 212 and thesubstrate 214 and expose the sites 315. The control system 228 caninclude one or more processors and circuits. In FIG. 2, the controlsystem 228 is illustrated as a single unit. It should be noted that inalternative embodiments the control system 228 can be designed withmultiple, spaced apart controllers.

FIG. 3A is a simplified top view of one non-exclusive embodiment of asubstrate 214 that has been processed with the exposure apparatus 210 ofFIG. 2. In this embodiment, the substrate 214 is a generally diskshaped, thin slice of semiconductor material, e.g. a semiconductorwafer, that serves as a substrate for photolithographic patterning.Typically, the disk shaped substrate 214 is divided into a plurality ofrectangular shaped sites 315 (e.g. chips) that are organized into aplurality of rows (along the X axis) and columns (along the Y axis). Asused herein, the term “site” shall mean an area on the substrate 214 towhich the entire or a portion of the mask pattern 346 (illustrated inFIG. 3C) has been transferred. For example, for a semiconductor wafer,each site 315 is one or more integrated circuits that include a numberof connected circuit elements that were transferred to the substrate 214by the exposure apparatus 210 of FIG. 2. In this example, each site 315contains one or more integral die piece(s) that can be sliced from thewafer.

In one embodiment, each site 315 is generally rectangular shaped and hasa first site dimension 348 (measured along the X axis) that is less thana second site dimension 350 (measured along the Y axis). In onenon-exclusive embodiment, each site 315 has a first site dimension 348of approximately twenty-six (26) millimeters, and a second sitedimension 350 of approximately thirty-three (33) millimeters.Alternatively, for example, each site 315 can have a first sitedimension 348 that is greater than or less than twenty-six (26)millimeters, and a second site dimension 350 that is greater than orless than thirty-three (33) millimeters. For example, each site 315 canhave a first site dimension 348 of approximately sixteen (16)millimeters, and a second site dimension 350 of approximately thirty-two(32) millimeters.

The size of the substrate 214 and the number of sites 315 on thesubstrate 214 can be varied. For example, the substrate 214 can have adiameter of approximately three hundred millimeters. Alternatively, thesubstrate 214 can have a diameter that is greater than or less thanthree hundred millimeters and/or the substrate 214 can have a shape thatis different than disk shaped (e.g. rectangular shaped). For example,the substrate 214 can be circularly shaped with a diameter approximatelyfour hundred fifty millimeters.

Further, for simplicity, in the embodiment illustrated in FIG. 3A, thesubstrate 214 is illustrated as having fifteen separate sites 315.Alternatively, for example, the substrate 214 can be separated intogreater than or fewer than fifteen sites 315.

In FIG. 3A, the sites 315 have been labeled “1” through “15” (onethrough fifteen). In this example, (i) the sites 315 labeled “1” through“3” are aligned in a first column along the Y axis; (ii) the sites 315labeled “4” through “6” are aligned in a second column along the Y axis;(iii) the sites 315 labeled “7” through “9” are aligned in a thirdcolumn along the Y axis; (iv) the sites 315 labeled “10” through “12”are aligned in a fourth column along the Y axis; and (v) the sites 315labeled “13” through “15” are aligned in a fifth column along the Yaxis. Additionally, the labels “1” through “15” represent onenon-exclusive embodiment of a sequence in which the mask pattern 346 canbe transferred to the sites 315 on the substrate 214. More specifically,as provided herein, the exposure apparatus 210 can first transfer themask pattern 346 to the site 315 labeled “1” (sometimes referred to asthe “first site”). Next, the exposure apparatus 210 can move the mask212 (illustrated in FIG. 2) and the substrate 214, and transfer the maskpattern 346 to the site 315 labeled “2” (sometimes referred to as the“second site”). Subsequently, and sequentially, the exposure apparatus210 can move the mask 212 and the substrate 214 to sequentially transferthe mask pattern 346 to the sites 315 labeled “3”, “4”, “5”, . . . and“15”.

Moreover, FIG. 3A includes an exposure pattern 352 (illustrated with adashed line) which further illustrates the order in which the maskpattern 346 is transferred to sites “1” through “3” in the first column.In this example, (i) the sites 315 labeled “1” through “3” aresequentially exposed as the substrate 214 is moved in a weaving(boustrophedonic) fashion and the mask 212 is moved back and forth. Morespecifically, the exposure pattern 352 comprises a plurality of scanningoperations 354 and a plurality of stepping operations 356, wherein thescanning operations 354 and the stepping operations 356 alternate sothat the exposure proceeds in a scan-step-scan-step-scan fashion. Asprovided herein, the scanning 354 of each site 315 occurs as thesubstrate 214 is moved along a scan axis 358 (i.e., the X axis) acrossthe first site dimension 348, and the stepping 356 in between exposuresof sites 315 occurs as the substrate 214 is moved along a step axis 360(i.e., the Y axis).

It should be noted that with the design illustrated in FIG. 3A, thescanning operations 354 occur while the substrate 214 is moved along thefirst site dimension 348 and stepping operations 356 occur while thesubstrate 214 is moved along the second site dimension 350. This resultsin shorter scanning times and longer stepping times compared to theprior art.

It should also be noted that in this example, the site 315 that isexposed first and the order in which the columns are exposed can bedifferent than that illustrated in FIG. 3A. Further, the site 315 thatis first exposed can be located away from the edge of the substrate 214

Additionally, FIG. 3A illustrates the pattern beam 236 that is directedat the first site “1” on the substrate 214. The pattern beam 236 isdiscussed in more detail with reference to FIGS. 3C-3E.

FIG. 3B is a simplified illustration of one embodiment of a field ofview 331 (illustrated with a dashed circle) of the projection opticalassembly 220 (illustrated in FIG. 2). As used herein, the term field ofview 331 shall mean the maximum image area over which the projectionoptical assembly 220 can provide a sufficiently accurate image of themask pattern. As provided herein, in certain embodiments, the field ofview 331 of the projection optical assembly 220 must be relatively largein order to transfer a relatively large pattern beam 236 (illustrated inFIG. 3A) to the site 315.

In one embodiment, the field of view 331 defines a rectangular shapedused field 362 (illustrated with a box with “X”'s) that includes a firstfield dimension 364 that is measured along the first axis (the X axis)and a second field dimension 366 that is measured along the second axis(the Y axis). In this embodiment, the second field dimension 366 islarger than the first field dimension 366.

In certain embodiments, the projection optical assembly 220 is designedso that the first field dimension 364 is less than the first sitedimension 348 (illustrated in FIG. 3A) and the second field dimension366 is equal to or greater than the second site dimension 350.

In one non-exclusive example, each site 315 has a first site dimension348 of twenty-six (26) millimeters and a second site dimension 350 ofthirty-three (33) millimeters. In this example, the second fielddimension 366 can be approximately thirty-three (33) millimeters, andthe first field dimension 364 is less than twenty-six (26) millimeters.As non-exclusive examples, the first field dimension 364 can beapproximately 2, 3, 4, 5, or 5.5 millimeters. Further, as non-exclusiveexamples, the second field dimension 366 can be approximately 29, 30,31, 32, 34, or 35 millimeters

Further, comparing prior art FIG. 1B and FIG. 3B, the used field 362 ofFIG. 3B has been rotated by approximately 90 degrees from theorientation of the used field 19P in the prior art (as illustrated inFIG. 1B). In one non-exclusive embodiment, in order to minimize theimpact of the orientation change, the edge of the used field 362 can bemoved closer to an optical axis 368 of the projection optical assembly220. In this embodiment, for example, the offset distance 368A is about1.25 millimeters, instead of the prior art design of 2.50 millimetersillustrated in FIG. 1B. Further, the first field dimension 364 of theused field 362 is less than the prior art design described above. Theresulting maximum field point is now 16.92 millimeters for a fielddiameter 368B of 33.84 millimeters as calculated in Equation 2.

$\begin{matrix}{{2*\sqrt{16.5^{2} + \left( {2.5 + 1.25} \right)^{2}}} = {33.84\mspace{14mu} {{mm}\mspace{20mu} \left( {33\mspace{14mu} {mm}\mspace{14mu} {field}\mspace{14mu} {height}} \right)}}} & \left( {{Equation}\mspace{14mu} 2} \right)\end{matrix}$

Additionally, it is important to look at the approximate gain inthroughput obtained by increasing the size of the used field 362 of theprojection optical assembly 220 and changing the scan direction fromacross the second site dimension 350 to across the first site dimension348.

More specifically, utilizing a slightly larger used field 362 size of 33millimeters by 2.5 millimeters for optical assembly 220, scanning theused field 362 across the first site dimension 348 instead of across thesecond site dimension 350, with an average wafer stage acceleration of2.5G in X axis and Y axis, an average mask 212 acceleration of 10G, anda substrate 214 scan velocity of 0.7 m/s, the maximum throughput is 274wafers per hour. The gain is 28 WPH, or an 11.5% gain in throughput overthe prior art described in the background. Alternatively, in certainembodiments, the idea of scanning the used field 362 across the firstfield dimension 364 could be used to decrease the requirements foracceleration and maximum scanning velocity of the substrate stageassembly 224 (illustrated in FIG. 2) and/or the mask stage assembly 222(illustrated in FIG. 2), while still maintaining the same or betterthroughput than is possible in the prior art.

FIG. 3C is a simplified top illustration of the mask 212 and a portionof the substrate 214 in a side-by-side arrangement, at the start of anexposure of the first site 1 (illustrated as a box). It should be notedthat the components of the exposure apparatus 210 (illustrated in FIG.2) are not shown in FIGS. 3C-3E for clarity. Further, it should also benoted that the mask 212 and the substrate 214 are shown in aside-by-side arrangement during exposure and that FIGS. 3C-3E are onlyillustrated in this configuration so that the relative positions ofthese components can be better understood. Additionally, in theseFigures, the mask pattern 346 is illustrated as being approximately thesame size as each site 315. However, in the event that the projectionoptical assembly 220 has a reduction factor of 4, the mask pattern 346can be four times larger than the size of each site 315. Moreover, FIG.3C also illustrates at least a portion of sites 2 through 9. In thisembodiment, each site 315 includes a site left side 315A, an opposedsite right side 315B, and a site center 315C (only one is illustratedwith a FIG. 3C illustrates that the mask 212 includes the mask pattern346 (illustrated as a box) that includes the features that are to betransferred to the substrate 214. In this embodiment, the mask pattern346 includes a pattern left side 346A, and opposed pattern right side346B, and a pattern center 346C (illustrated as with a “+”).

At the start of exposure of the first site 1, the control system 228(illustrated in FIG. 2) controls the illumination system 218(illustrated in FIG. 2) to generate the slit shaped illumination beam235 (illustrated as “o”'s) that is directed at the mask 212, andcontrols the mask stage assembly 222 (illustrated in FIG. 2) to positionthe mask 212 so that the mask pattern 346 is illuminated near thepattern left side 346A. This causes the resulting pattern beam 236(illustrated as “\”'s) to be directed at a corresponding portion of thefirst site 1. In the illustrations, the left side of the mask patternarea corresponds to the left side of the substrate site. Depending onthe optical design, however, the image may be reversed, so the rightside of the mask pattern area corresponds to the left side of thesubstrate site.

At the beginning of the exposure of the first site 1, (i) the patterncenter 346C is located at a first mask position, which is referenced asXm1 along the scan axis 358 and Ym1 along the step axis 360, and (ii)the site center 315C of the first site 1 is located at a site firstposition, which is referenced as Xs1 along the scan axis 358 and Ys1along the step axis 360.

Further, at the beginning of the exposure, the control system 228(illustrated in FIG. 2) (i) controls the mask stage assembly 222 so thatthe mask 212 is being moved at a constant velocity in a first scandirection 370A (from right to left in FIG. 3A) along the scan axis 358(the X axis), and (ii) controls the substrate stage assembly 224(illustrated in FIG. 2) so that the substrate 214 is also being moved ata constant velocity in the first scan direction 370A along the scan axis358. With the present design, in certain embodiments, both the mask 212and the substrate 214 are moved synchronously in the same scan direction370A. Further, for example, if the projection optical assembly 220(illustrated in FIG. 2) has a reduction factor of four, the mask 212 ismoved at a rate that is four times greater than that of the substrate214. Alternatively, the mask 212 and substrate 214 can be moved inopposite directions along the scan axis 358 during scanning of the sites315.

Additionally, as illustrated in FIG. 3C, the pattern beam 236 isgenerally rectangular slit shaped and includes a first beam dimension372 along the first axis (the X axis) and a second beam dimension 374along the second axis (the Y axis). In this embodiment, the second beamdimension 374 is larger than the first beam dimension 372. In certainembodiments, the exposure apparatus 210 (illustrated in FIG. 2) isdesigned so that the first beam dimension 372 is less than the firstsite dimension 348 (illustrated in FIG. 3A) and the second beamdimension 374 is equal to the second site dimension 350 (illustrated inFIG. 3A). In one non-exclusive example, each site 315 has a first sitedimension 348 of twenty-six (26) millimeters and a second site dimension350 of thirty-three (33) millimeters. In this example, the second beamdimension 374 can be approximately thirty-three (33) millimeters, andthe first beam dimension 372 is less than twenty-six (26) millimeters.As non-exclusive examples, the first beam dimension 372 can beapproximately 2, 3, 4, 5, or 5.5 millimeters. Alternatively, forexample, the second beam dimension 374 can be approximately 29, 30, 31,32, 34, or 35 millimeters.

FIG. 3D is a simplified top illustration of the mask 212 and a portionof the substrate 214 in a side-by-side arrangement, at the end of theexposure of the first site 1. At this time, the control system 228(illustrated in FIG. 2) controls the illumination system 218(illustrated in FIG. 2) to generate the slit shaped illumination beam235 (illustrated as “o”'s) that is directed at the mask 212, andcontrols the mask stage assembly 222 (illustrated in FIG. 2) to positionthe mask 212 so that the mask pattern 346 is illuminated near thepattern right side 346B. This causes the resulting pattern beam 236(illustrated as “\”'s) to be directed at a portion of the first site 1.

At the end of the exposure of the first site 1, (i) the pattern center346C is located at a second mask position, which is referenced as Xm2along the scan axis 358 and Ym1 along the step axis 360, and (ii) thesite center 315C of the first site 1 is located at a site secondposition, which is referenced as Xs2 along the scan axis 358 and Ys1along the step axis 360.

It should be noted that (i) the difference between the first maskposition Xm1 and the second mask position Xm2 along the scan axis 358 isreferred to herein as a mask exposure distance 376, and (ii) thedifference between the first substrate position Xs1 and the secondsubstrate position Xs2 along the scan axis 358 is referred to herein asa site exposure distance 378. In this example, (i) the mask exposuredistance 376 is the distance in which the mask 212 is moved along thescan axis 358 during the exposure (i.e., the scanning operation 354 asillustrated in FIG. 3A) of the first site 1, and (ii) the site exposuredistance 378 is the distance in which the substrate 314 is moved alongthe scan axis 358 during the exposure of the first site 1.

For clarity, in FIG. 3D, the mask exposure distance 376 is illustratedas being equal to the site exposure distance 378. Alternatively, in theevent the projection optical assembly 220 (illustrated in FIG. 1) has areduction factor of four, the mask exposure distance 376 is four timeslarger than the site exposure distance 378.

Referring to FIGS. 3C and 3D, it should also be noted that the entiremask pattern 346 is scanned to the first site 1 during movement of themask 212 the mask exposure distance 376. Additionally, the exposure ofthe first site 1 is halted once the pattern beam 236 is directed at thepattern right side 346B.

Further, it should be noted that during the exposure of the sites 315(i.e., during the scanning operations 354), the control system 228controls the mask stage assembly 222 so that the mask 212 isapproximately not moved along the step axis 360 (the Y axis), and thecontrol system 228 controls the substrate stage assembly 224(illustrated in FIG. 2) so that the substrate 214 is approximately notmoved along the step axis 360 (the Y axis). Moreover, during scanning,both the mask 212 and the substrate 214 are moved at a constant velocityalong the scan axis 358.

FIGS. 3E is a simplified top illustration of the mask 212 and a portionof the substrate 214 in a side-by-side arrangement, at the start of anexposure of the second site 2. At this time, the control system 228(illustrated in FIG. 2) controls the illumination system 218(illustrated in FIG. 2) to generate the slit shaped illumination beam235 (illustrated as “o”'s) that is directed at the mask 212, andcontrols the mask stage assembly 222 (illustrated in FIG. 2) to positionthe mask 212 so that the mask pattern 346 is illuminated near thepattern right side 346B. This causes the resulting pattern beam 236(illustrated as “\”'s) to be directed at a corresponding portion of thesecond site 2.

At the beginning of the exposure of the second site 2, (i) the patterncenter 346C is again located at the second mask position, which isreferenced as Xm2 along the scan axis 358 and Ym1 along the step axis360, and (ii) the site center 315C of the first site 1 is located at asite third position, which is referenced as Xs2 along the scan axis 358and Ys2 along the step axis 360.

Basically, in between exposures (i.e., during the stepping operations356 as illustrated in FIG. 3A), (i) the substrate 214 is stepped withthe substrate stage assembly 224 (illustrated in FIG. 2) so that thesecond site 2 is being moved towards the field of view 331 (illustratedin FIG. 3B) of the projection optical assembly 220 (illustrated in FIG.2), and (ii) the position of the mask pattern 346 is reset along thescan axis 358 to the second mask position Xm2 with the mask stageassembly 222 (illustrated in FIG. 2). It should be noted that the maskpattern 346 is moved past the second mask position Xm2 after theexposure because the mask 212 is moved at a constant velocity during theentire exposure and the mask 212 must be decelerated after the exposure.The mask is subsequently accelerated back toward the second maskposition Xm2 prior to the next exposure, so that the mask 212 can againbe moved at a constant velocity from the second mask position Xm2 to thefirst mask position Xm1 during the subsequent exposure of the secondsite 2.

It should also be noted that the difference between the site firstposition Ys1 and the site third position Ys2 along the step axis 358 isreferred to herein as a site step distance 380. In this example, thesite step distance 380 is the distance in which the substrate 314 ismoved along the step axis 360 between the exposure of the first site 1and the exposure of the second site 2 (i.e., during the steppingoperation 356).

Further, at the beginning of the exposure, the control system 228(illustrated in FIG. 2) (i) controls the mask stage assembly 222 so thatthe mask 212 is being moved at a constant velocity in a second scandirection 370B (from left to right in FIG. 3A) along the scan axis 358(the X axis) from the second mask position Xm2 back toward the firstmask position Xm1, and (ii) controls the substrate stage assembly 224(illustrated in FIG. 2) so that the substrate 214 is also being moved ata constant velocity in the second scan direction 370B along the scanaxis 358 from Xs2 back toward Xs1. With the present design, in certainembodiments, both the mask 212 and the substrate 214 are movedsynchronously in the same scan direction 370B. Further, for example, ifthe projection optical assembly 220 (illustrated in FIG. 2) has areduction factor of four, the mask 212 is moved at a rate that is fourtimes greater than that of the substrate 214. Alternatively, as notedabove, the mask 212 and substrate 214 can be moved in oppositedirections along the scan axis 358 during scanning of the sites 315.

FIG. 3F is a simplified illustration of one non-exclusive embodiment ofthe projection optical assembly 220. In this embodiment, the projectionoptical assembly 220 includes the plurality of spaced apart opticalelements 220A and an optical housing 382A. In this embodiment, theprojection optical assembly 220 has an optical axis 382B and the opticalelements 220A are aligned along the optical axis 382B.

As provided herein, the design, positioning, and number of opticalelements 220A can be varied to achieve the relatively large field ofview 331 (illustrated in FIG. 3B) and described above so that one ormore of the sites 315 (illustrated in FIG. 3A) of the substrate 214(illustrated in FIG. 3A) can be scanned along their short dimension. InFIG. 3F, the projection optical assembly 220 is illustrated as havingeleven optical elements 220A. Alternatively, the projection opticalassembly 220 can be designed with greater or fewer than eleven opticalelements 220A. As provided herein, the number of optical elements 220Acan be greater than what is typical utilized in prior art projectionoptical assemblies to cancel off-axis aberrations. In FIG. 3F, theoptical elements 220A are aligned along the common optical axis 382B.Alternatively, the optical path can be folded to allow for the use ofadditional optical elements 220A for aberration correction withoutincreasing the distance between the mask and the substrate.

In one embodiment, one or more of the optical elements 220A is a lensthat is made of high quality fused silica (SiO2). Alternatively, one ormore of the optical elements 220A can be made of another material.

In one embodiment, in order to achieve a larger field of view 331, oneor more of the optical elements 220A can have an element diameter 320Bthat is greater than approximately three hundred fifty millimeters (350mm). For example, in alternative non-exclusive embodiments, one or moreof the optical elements 220A can have an element diameter 320B that isgreater than approximately 360, 370, 375, 380, 385, or 390 millimeters.

Further, in order to achieve a larger field of view 331 with lessoff-axis aberrations, a separation distance 320C between a top of anuppermost element 320U of the projection optical assembly 220 and abottom of a lowermost element 320L can be greater than approximately 1.4meters. For example, in alternative non-exclusive embodiments, theseparation distance 320C can be greater than approximately 1.5, 1.6,1.7, 1.8, 1.9, or 2 meters for a NA=1.3 system.

FIG. 4 is a schematic illustration of a second embodiment of an exposureapparatus 410 having features of the present invention. In FIG. 4, theexposure apparatus 410 includes an apparatus frame 416, an illuminationsystem 418, an optical assembly 420, a first mask stage assembly 422A, asecond mask stage assembly 422B, a substrate stage assembly 424, ameasurement system 426, and a control system 428. Many of thesecomponents are similar in design to the corresponding similarly namedcomponents described above and illustrated in FIG. 2.

In this embodiment, the exposure apparatus 410 utilizes multiple masks412A, 412B to transfer images to a substrate 414 that includes aplurality of sites 415. With this embodiment, in certain embodiments,the masks 412A, 412B are substantially identical in design, and at leasttwo adjacent sites 415 on the substrate 414 can be sequentially exposedwithout stopping the substrate 414 and without changing the movementdirection of substrate 414. Stated in another fashion, at least twosites 415 can be scanned without stepping the substrate 414. This allowsfor higher overall throughput for the exposure apparatus 410.

Further, in this embodiment, the exposure apparatus 410 is a scanningtype photolithography system (i) that first exposes a first mask pattern429A from the first mask 412A onto one of the sites 415 of the substrate414 while the first mask 412A and the substrate 414 are movingsynchronously, and (ii) that subsequently exposes a second mask pattern429B from the second mask 412B onto an adjacent site 415 on thesubstrate 414 while the second mask 412B and the substrate 414 aremoving synchronously. Alternatively, the masks 412A, 412B can bedifferent in design and the exposure apparatus 410 can be used to scanboth the first mask pattern 429A and the second mask pattern 429B ontothe same site 415, simultaneously or at different times.

An additional discussion of a multiple mask exposure system is disclosedin concurrently filed application Ser. No. ______, entitled “EXPOSUREAPPARATUS THAT UTILIZES MULTIPLE MASKS” (PA1017-00/4990/Roeder Ref.No.11269.156), which is assigned to the assignee of the presentinvention, and is incorporated by reference herein as far as permitted.

An additional discussion regarding another type of exposure apparatus isdisclosed in concurrently filed application Ser. No. ______, entitled“EXPOSURE APPARATUS WITH SCANNING ILLUMINATION BEAM”(PAO1003-00/04982/Roeder Ref. No. 11269.177), which is assigned to theassignee of the present invention, and is incorporated by referenceherein as far as permitted.

The illumination system 418 generates a first illumination beam 435A(irradiation) of light energy that is selectively directed at the firstmask 412A, and a second illumination beam 435B (irradiation) of lightenergy that is selectively directed at the second mask 412B. In certainembodiments, the illumination system 418 generates both illuminationbeams 435A, 435B at the same time. Alternatively, in certain designs,the illumination system 418 will sequentially generate the illuminationbeams 435A, 435B during the sequential exposure of the sites 415.

In one embodiment, the illumination system 418 includes (i) a firstillumination source 432A that emits the first illumination beam 435A;(ii) a first illumination optical assembly 434A that guides the firstillumination beam 435A from the first illumination source 432A to nearthe first mask 412A; (iii) a second illumination source 432B that emitsthe second illumination beam 435B; and (iv) a second illuminationoptical assembly 434B that guides the second illumination beam 435B fromthe second illumination source 432B to near the second mask 412B.Alternatively, the illumination system 418 can be designed with a singleillumination source that generates an illumination beam that is split orselectively redirected to create the multiple separate illuminationbeams 435A, 435B.

The first illumination beam 435A illuminates the first mask 412A togenerate a first pattern beam 436A (e.g. images from the first mask412A) that exposes the substrate 414. Similarly, the second illuminationbeam 435B illuminates the second mask 412B to generate a second patternbeam 436B (e.g. images from the second mask 412B) that exposes thesubstrate 414.

The optical assembly 420 projects and/or focuses the first pattern beam436A and the second pattern beam 436B onto the substrate 414. In theembodiment illustrated in FIG. 4, the optical assembly 420 includes (i)a first optical inlet 421A that receives the first pattern beam 436A,(ii) a second optical inlet 421B that receives the second pattern beam436B, and (iii) an optical outlet 421C that directs both pattern beams436A, 436B at the substrate 414. Further, in this embodiment, (i) thefirst optical inlet 421A includes a first inlet axis 421D, (ii) thesecond optical inlet 421B includes a second inlet axis 421E, and (iii)the optical outlet 421C includes an outlet axis 421F. The opticalassembly 420 is described in more detail below.

The first mask stage assembly 422A holds and positions the first mask412A relative to the optical assembly 420 and the substrate 414.Similarly, the second mask stage assembly 422B holds and positions thesecond mask 412B relative to the optical assembly 420 and the substrate414. Further, the substrate stage assembly 424 holds and positions thesubstrate 414 with respect to the pattern beams 436A, 436B. The stageassemblies 422A, 422B, 424 can be similar in design to the correspondingcomponents described above with reference to FIG. 2.

The control system 428 receives information from the measurement system426 and controls the stage assemblies 422A, 422B, 424 to preciselyposition the masks 412A, 412B and the substrate 414. Further, thecontrol system 428 can control the operation of the illumination system418 to selectively and independently generate the illumination beams435A, 435B.

FIG. 5A is a simplified top view of one non-exclusive embodiment of asubstrate 414 that can be exposed with the exposure apparatus 410described above. The design of the substrate 414 is similar to thesubstrate 214 described above and illustrated in FIG. 3A. However, inFIG. 5A, the order in which the sites 415 are exposed is different. Morespecifically, two sites 415 are scanned along the X axis (e.g. the shortdimension of the sites 415) before being stepped along the Y axis.

In this embodiment, the substrate 414 is illustrated as havingthirty-two separate sites 415, with each site 415 having a first sitedimension 548 (measured along the X axis) that is less than a secondsite dimension 550 (measured along the Y axis). In one non-exclusiveembodiment, each site 415 has a first site dimension 548 ofapproximately twenty-six (26) millimeters, and a second site dimension550 of approximately thirty-three (33) millimeters.

In FIG. 5A, the sites 415 have been labeled “1” through “32” (onethrough thirty-two). In this example, the labels “1” through “32”represent one non-exclusive embodiment of the sequence in which the maskpatterns 436A, 436B can be transferred to the sites 415 on the substrate414. More specifically, as provided herein, the exposure apparatus 410can transfer the first mask pattern 429A from the first mask 412A to thesite 415 labeled “1” (sometimes referred to as the “first site”). Next,the exposure apparatus 410 can transfer the second mask pattern 429Bfrom the second mask 412B to the site 415 labeled “2” (sometimesreferred to as the “second site”). Subsequently, the exposure apparatus410 can transfer the second mask pattern 429B from the second mask 412Bto the site 415 labeled “3” (sometimes referred to as the “third site”).Next, the exposure apparatus 410 can transfer the first mask pattern429A from the first mask 412A to the site 415 labeled “4” (sometimesreferred to as the “fourth site”). Subsequently, the exposure apparatus410 can continue repeating the sequencing of the transferring of thefirst mask pattern 429A and the second mask pattern 429B (i.e., in afirst, second, second, first sequence) to the sites 415 labeled “6”,“7”, “8”, . . . and “32”. In an alternative embodiment, the exposureapparatus 410 can alternate between transferring the first mask pattern429A and the second mask pattern 429B to the sites 415 labeled “1”, “2”,“3”, “4”, “5”, . . . and “32” (i.e., the first mask pattern 429A istransferred to all the odd numbered sites 415, and the second maskpattern 429B is transferred to all the even numbered sites 415).

Moreover, FIG. 5A includes an exposure pattern 552A (illustrated with adashed line) which further illustrates the order in which the maskpatterns 429A, 429B are transferred to sites 415. In this example, theexposure pattern 552A again includes a plurality of scanning operations552B and a plurality of stepping operations 552C, wherein the scanningoperations 552B and the stepping operations 552C alternate so that theexposure proceeds in a scan-step-scan-step-scan fashion. In thisembodiment, the scanning 552B occurs as the substrate 414 is moved alonga scan axis 558 (the X axis), and the stepping 552C occurs as thesubstrate 414 is moved along a step axis 560 (the Y axis).

It should be noted that with the use of multiple masks 412A, 412B(illustrated in FIG. 4), two adjacent sites 415 (e.g. 1 and 2) can bescanned sequentially while moving the substrate 414 at a constantvelocity along the scan axis 558. As a result thereof, the substrate 414does not have to be stepped and reversed in direction between theexposures of the sites 415. Instead, for the embodiment illustrated inFIG. 5A, the substrate 414 is only stepped between the exposure of pairsof adjacent sites 415 aligned on the scan axis 558. Stated in anotherfashion, with the present design, there is one stepping motion for everytwo sites 415 scanned. This results in fewer steps and significantlyimproved throughput from the exposure apparatus 410.

It should be noted that in this example, the site 415 that is exposedfirst and the order in which the sites 415 are exposed can be differentthan that illustrated in FIG. 5A. Further, the site 415 that is firstexposed can be located away from the edge of the substrate 414.

FIG. 5B is a simplified illustration of one embodiment of a field ofview 531 (illustrated with a dashed circle) of the optical assembly 420(illustrated in FIG. 4). As provided herein, in certain embodiments, thefield of view 531 of the optical assembly 420 must be relatively largein order to transfer a relatively large pattern beam 436A, 436B(illustrated in FIG. 4) to the site 415 (illustrated in FIG. 5A).

In one embodiment, the field of view 531 defines (i) a first used field562A (illustrated as a box with solid lines) in which the first patternbeam 436A (illustrated in FIG. 4) exits the optical assembly 420, and(ii) and a spaced apart second used field 562B (illustrated as a boxwith dashed lines) in which the second pattern beam 436B (illustrated inFIG. 4) exits the optical assembly 420. In one embodiment, the firstused field 562A and the second used field 562B are substantially similarin shape and size. As illustrated, the first used field 562A has arectangular shape that includes a first field dimension 564 that ismeasured along the first axis (the X axis) and a second field dimension566 that is measured along the second axis (the Y axis). In thisembodiment, the second field dimension 566 is larger than the firstfield dimension 564.

In certain embodiments, the optical assembly 420 is designed so that thefirst field dimension 564 is less than the first site dimension 548(illustrated in FIG. 5A) and the second field dimension 566 is equal tothe second site dimension 550 (illustrated in FIG. 5A). In onenon-exclusive example, each site 415 has a first site dimension 548 oftwenty-six (26) millimeters and a second site dimension 550 ofthirty-three (33) millimeters. In this example, the second fielddimension 566 can be approximately thirty-three (33) millimeters, andthe first field dimension 564 is less than twenty-six (26) millimeters.As non-exclusive examples, the first field dimension 564 can beapproximately 2, 2.5, or 3 millimeters.

In one embodiment, the optical assembly 420 has a numerical aperture(NA) of at least approximately 1.30. In order to minimize or correctaberrations of the optical assembly 420 at such a high NA, the opticalassembly 16 can be catadioptric. In one embodiment, the used fields562A, 562B are off-axis in order to avoid obscurations from the relativesurfaces. Stated in another fashion, in the embodiment illustrated inFIG. 5B, (i) the first used field 562A is offset from an optical axis568 of the optical assembly 420 a first offset distance 568A, (ii) thesecond used field 562B is offset from the optical axis 568 a secondoffset distance 568B, and (iii) the first used field 562A and the secondused field 562B are spaced apart a separation distance 568C. Moreover,the used fields 562A, 562B are positioned on opposite sides of theoptical axis 568, and the used fields 562A, 562B are substantiallyparallel to each other. In one non-exclusive embodiment, each offsetdistance 568A, 568B is approximately 2.5 millimeters, and the separationdistance 568C is approximately 5 millimeters. Alternatively, the offsetdistances 568A, 568B can be greater than or less than 2.5 millimeters.

FIGS. 6A-6D further illustrate one non-exclusive embodiment of how asubstrate 414 can be exposed utilizing the exposure apparatus 410illustrated in FIG. 4. More specifically, FIG. 6A is a simplified sideview of the first mask 412A, the second mask 412B, the optical assembly420, and the substrate 414 at a beginning of an exposure of a first site1. At the start of exposure of the first site 1, the control system 428(illustrated in FIG. 4) controls the illumination system 418(illustrated in FIG. 4) to generate the slit shaped first illuminationbeam 435A that is directed at the first mask 412A, and controls thefirst mask stage assembly 422A (illustrated in FIG. 4) to position thefirst mask 412A so that the first mask pattern 429A is illuminated neara right side of the pattern 429A. This causes a resulting first patternbeam 436A to be directed by the optical assembly 420 at the right sideof the first site 1.

Additionally, as illustrated in FIG. 6A, the first pattern beam 436A isinitially directed toward the first optical inlet 421A along the firstinlet axis 421D. The first pattern beam 436A is subsequently redirectedand focused within the optical assembly 420 until the first pattern beam436A is ultimately directed by the optical assembly 420 from the opticaloutlet 421C offset from the outlet axis 421F. More particularly, thefirst pattern beam 436A is directed by the optical assembly 420 throughthe optical outlet 421C toward a right side of the first site 1.

Further, at the beginning of the exposure of the first site 1, thecontrol system 428 (i) controls the first mask stage assembly 422A sothat the first mask 412A is being moved at a constant velocity in afirst scan direction 558A (from left to right in FIG. 6A) along the scanaxis 558 (the X axis), and (ii) controls the substrate stage assembly424 (illustrated in FIG. 4) so that the substrate 414 is also beingmoved at a constant velocity in the first scan direction 558A along thescan axis 558. With the present design, in certain embodiments, both thefirst mask 412A and the substrate 412 are moved synchronously in thesame scan direction 558A. Further, for example, if the optical assembly420 has a reduction factor of four, the first mask 412A is moved at arate that is four times greater than that of the substrate 414.Alternatively, the first mask 412A and the substrate 414 can be moved inopposite directions along the scan axis 558 during scanning of the sites415.

As the first mask 412A is being moved in the first scan direction 558A,the first pattern beam 436A continues to illuminate a portion of thefirst mask 412A from initially near the right side toward the left side.At the same time, the substrate 414 is being moved in the first scandirection 558A so that the first pattern beam 436A is directed initiallyat the right side and continuously and subsequently toward the left sideof the substrate 414.

FIG. 6B is a simplified side view of the first mask 412A, the secondmask 412B, the optical assembly 420, and the substrate 414 at abeginning of an exposure of the second site 2.

At the start of exposure of the second site 2, the control system 428(illustrated in FIG. 4) controls the illumination system 418(illustrated in FIG. 4) to generate the slit shaped second illuminationbeam 435B that is directed at the second mask 412B, and controls thesecond mask stage assembly 422B (illustrated in FIG. 4) to position thesecond mask 412B so that a second mask pattern 429B is illuminated nearthe right side of the pattern 429B. This causes a resulting secondpattern beam 436B to be directed by the optical assembly 420 at aportion of the second site 2.

Additionally, as illustrated in FIG. 6B, the second pattern beam 436B isinitially directed toward a second optical inlet 421B of the opticalassembly 420 along a second inlet axis 421E. The second pattern beam436B is subsequently redirected and focused within the optical assembly420 until the second pattern beam 436B exits the optical outlet 421Coffset from the outlet axis 421F.

Further, at the beginning of the exposure of the second site 2, thecontrol system 428 (i) controls the second mask stage assembly 422B sothat the second mask 412B is being moved at a constant velocity in thefirst scan direction 558A along the scan axis 558, and (ii) controls thesubstrate stage assembly 424 (illustrated in FIG. 4) so that thesubstrate 414 is also being moved at a constant velocity in the firstscan direction 558A. With the present design, in certain embodiments,both the second mask 412B and the substrate 414 are moved synchronouslyin the same scan direction 558A. Alternatively, the second mask 412B andthe substrate 414 can be moved in opposite directions along the scanaxis 558 during scanning of the sites 415.

It should be noted that with the design of the optical assembly 420 asillustrated herein, the exposure of the first site 1 and the second site2 occurs with the substrate 414 being moved in the same first scandirection 558A at a substantially constant velocity. This enablesgreater throughput for the exposure apparatus 410 (illustrated in FIG.4).

FIG. 6C is a simplified side view of the first mask 412A, the secondmask 412B, the optical assembly 420, and the substrate 414 at abeginning of an exposure of the third site 3. It should be noted thatafter the exposure of the second site illustrated in FIG. 6B, thesubstrate 414 is stepped into the page along the Y axis.

During the exposure of the third site 3, the control system 428(illustrated in FIG. 4) controls the illumination system 418(illustrated in FIG. 4) to generate the slit shaped second illuminationbeam 435B that is directed at the second mask 412B, and controls thesecond mask stage assembly 422B (illustrated in FIG. 4) to position thesecond mask 412B so that the second mask pattern 429B is illuminatednear its left side. This causes a resulting second pattern beam 436B tobe directed by the optical assembly 420 at a portion of the third site3.

Further, during the exposure of the third site 3, the control system 428(i) controls the second mask stage assembly 422B so that the second mask412B is being moved at a constant velocity in a second scan direction558B (from right to left in FIG. 6C, opposite from the first scandirection 558A) along the scan axis 558 (the X axis), and (ii) controlsthe substrate stage assembly 424 (illustrated in FIG. 4) so that thesubstrate 414 is also being moved at a constant velocity in the secondscan direction 558B.

FIG. 6D is a simplified side view of the first mask 412A, the secondmask 412B, the optical assembly 420, and the substrate 414 at abeginning of an exposure of the fourth site 4. At the start of exposureof the fourth site 4, the control system 428 (illustrated in FIG. 4)controls the illumination system 418 (illustrated in FIG. 4) to generatethe slit shaped first illumination beam 435A that is directed at thefirst mask 412A, and controls the first mask stage assembly 422A(illustrated in FIG. 4) to position the first mask 412A so that thefirst mask pattern 429A is illuminated near its left side. This causes aresulting first pattern beam 436A to be directed by the optical assembly420 at a portion of the fourth site 4. In certain embodiments, theexposure of the fourth site 4 using reticle 412A can begin before theexposure of the third site 3 using reticle 412B has finished.

During the exposure of the fourth site 4, the control system 428 (i)controls the first mask stage assembly 422A so that the first mask 412Ais being moved at a substantially constant velocity in the second scandirection 558B along the scan axis 558, and (ii) controls the substratestage assembly 424 (illustrated in FIG. 4) so that the substrate 414 isalso being moved at a substantially constant velocity in the second scandirection 558B.

It should be noted that with the design of the optical assembly 420 asillustrated herein, the exposure of the third site 3 and the fourth site4 occur with the substrate 414 being moved in the same second scandirection 558B along the scan axis 558. Further, the four sites 1-4 canbe exposed with only one stepping motion.

FIGS. 7A-7I further illustrate one embodiment of how four sites labeled1-4 can be exposed using the exposure apparatus 410 as illustrated inFIG. 4 and as described above. In these Figures, the box with solidlines represents the first used field 762A, the box with dashed linesrepresents the second used field 762B, and the slashes represent therespective pattern beam. Further, in these Figures, the arrow representsthe direction in which the substrate is being moved during scanning atthat particular time. During the exposure of the sites 1-4, thesubstrate is moved down the page, then left, and then up. In FIGS.7A-7I, it appears that the used fields 762A, 762B move, however, thesubstrate is actually being moved relative to the used fields 762A,762B.

Starting with FIG. 7A, at the beginning of the exposure of the firstsite 1, the first pattern beam 736A (illustrated with slashes) isexposing the first site 1 and there is no second pattern beam. At thistime, the first used field 762A is positioned over the first site 1, andthe second used field 762B is not over any of the sites 1-4.

Next, referring to FIG. 7B, after the first site 1 is exposed, the firstused field 762A is positioned over the second site 2, and the secondused field 762B is positioned over the first site 1. At this timeneither of the pattern beams is being generated. The amount of time inwhich the two beams are off is determined by the distance between theslits and the motion of the stages.

Subsequently, referring to FIG. 7C, once the second used field 762B ispositioned over the second site 2, the second pattern beam 736B(illustrated with slashes) begins to expose the second site 2, and thereis no first pattern beam.

Next, referring to FIG. 7D, while the second used field 762B is stillpositioned over the second site 2, the second pattern beam 736B(illustrated with slashes) continues to expose the second site 2, andthere is no first pattern beam.

Subsequently, upon the completion of the exposure of the second site 2,the substrate is moved to the left. Referring to FIG. 7E, once thesecond used field 762B is positioned over the third site 3, the secondpattern beam 736B (illustrated with slashes) begins to expose the thirdsite 3, and there is no first pattern beam. At this time, the substrateis being moved up the page.

Next, referring to FIG. 7F, while the second used field 762B is stillpositioned over the third site 3, the second pattern beam 736B(illustrated with slashes) continues to expose the third site 3, andthere is no first pattern beam.

Subsequently, referring to FIG. 7G, after the third site 3 is exposed,the first used field 762A is positioned over the third site 3, and thesecond used field 762B is positioned over the fourth site 4. At thistime neither of the pattern beams are being generated.

Next, referring to FIG. 7H, once the first used field 762A is positionedover the fourth site 4, the first pattern beam 736A (illustrated withslashes) begins to expose the fourth site 4, and there is no secondpattern beam.

Subsequently, referring to FIG. 7I, while the first used field 762A isstill positioned over the fourth site 4, the first pattern beam 736A(illustrated with slashes) continues to expose the fourth site 4, andthere is no second pattern beam.

In this embodiment, the system is designed so that the second site 2 isnot exposed until after the exposure of the first site 1 is fullycompleted, and the fourth site 4 is not exposed until after the exposureof the third site 3 is fully completed. This requires an A-B-B-Aexposure sequence. The benefit of this sequence is that there is never atime when both pattern beams are required, so it is easier to use asingle illumination source 432A, 432B (illustrated in FIG. 4). Thedrawbacks of this sequence are (1) that the reticle stage accelerationmust be proportional to the substrate acceleration (e.g., in a 4×reduction system, the reticle acceleration is four times the substrateacceleration), and (2) that the scanning distance is longer than thatrequired for the sequence described below for FIGS. 8A-8I.

FIGS. 8A-8I further illustrate another embodiment of how four siteslabeled 1-4 can be exposed using the exposure apparatus 410 asillustrated in FIG. 4 and as described above. Similar to the embodimentillustrated in FIGS. 7A-71, in this embodiment, the box with solid linesis the first used field 862A, the box with dashed lines is the secondused field 862B, and the slashes represent the pattern beam. Further,the arrow again represents the direction in which the substrate is beingmoved during scanning at that particular time, with the substrateinitially being moved down the page, then left, and then up during theexposure of the four sites.

Starting with FIG. 8A, at the beginning of the exposure of the firstsite 1, the second pattern beam 836B (illustrated with slashes) isexposing the first site 1 and there is no first pattern beam. At thistime, both the first used field 862A and the second used field 862B arepositioned over the first site 1. Further, at this time, the substrateis being moved down the page.

Next, referring to FIG. 8B, during continuation of exposure of the firstsite 1, the first used field 862A is positioned over the second site 2,and the second used field 862B is positioned over the first site 1. Oncethe first used field 862A is positioned over the second site 2, thefirst pattern beam 836A (illustrated with slashes) begins to expose thesecond site 2. At the same time, the second pattern beam 836B(illustrated with slashes) is still being generated and is stillexposing the first site 1. Stated another way, at this time both of thepattern beams 836A, 836B are being generated, and the continuingexposure of the first site 1 coincides or overlaps with the beginning ofthe exposure of the second site 2.

Subsequently, referring to FIG. 8C, both the first used field 862A andthe second used field 862B are positioned over the second site 2. Oncethe second used field 862B is positioned over the second site 2, thesecond pattern beam is no longer being generated, but the first patternbeam 836A (illustrated with slashes) is still being generated and iscontinuing exposure of the second site 2.

Next, referring to FIG. 8D, only the second used field 862B is stillpositioned over the second site 2, and the first used field 862A is notpositioned over any of the sites. This is the condition after completionof the exposure of the second site 2. At this time, neither of thepattern beams are being generated, and the substrate is already steppingto the left.

Referring next to FIG. 8E, the second used field 862B is positioned overthe third site 3, and the first used field 862A is not positioned overany of the sites. At this time, neither of the pattern beams are beinggenerated. Further, at this time, the substrate is being moved up thepage, and is finishing its stepping motion to the left.

Next, referring to FIG. 8F, once the first used field 862A is positionedover the third site 3, the first pattern beam 836A (illustrated withslashes) begins to expose the third site 3. At this time, the secondused field 862B is still positioned over the third site 3, and no secondpattern beam is being generated.

Subsequently, referring to FIG. 8G, during continuation of exposure ofthe third site 3, the first used field 862A is still positioned over thethird site 3, and the second used field 862B is now positioned over thefourth site 4. Once the second used field 862B is positioned over thefourth site 4, the second pattern beam 836B (illustrated with slashes)begins to expose the fourth site 4. At the same time, the first patternbeam 836A (illustrated with slashes) is still being generated and isstill exposing the third site 3. Stated another way, at this time bothof the pattern beams 836A, 836B are being generated, and the continuingexposure of the third site 3 coincides or overlaps with the beginning ofthe exposure of the fourth site 4.

Next, referring to FIG. 8H, both the first used field 862A and thesecond used field 862B are now positioned over the fourth site 4. Oncethe first used field 862A is positioned over the fourth site 4, thefirst pattern beam is no longer being generated, but the second patternbeam 836B (illustrated with slashes) is still being generated and iscontinuing exposure of the fourth site 4.

Subsequently, referring to FIG. 81, only the first used field 862A isstill positioned over the fourth site 4, and the second used field 862Bis not positioned over any of the sites. At this time, neither of thepattern beams are being generated.

In this embodiment, the system is designed so that the exposure of thesecond site 2 is started prior to the exposure of the first site 1 beingfully completed.

Comparing the exposures illustrated in FIGS. 7A-7I with exposuresillustrated in FIGS. 8A-8I, the overall scanning distance is longer forthe embodiment illustrated in FIGS. 7A-7I. Therefore, the exposure ofFIG. 8A-8I is completed faster, leading to higher overall throughput,assuming the same scan velocity for the two cases. The B-A-A-B sequenceshown in FIGS. 8A-8I achieves this higher throughput by having time whenboth pattern beams are used simultaneously. The drawbacks of thissequence are (1) that the reticle stage acceleration must beproportional to the substrate acceleration (e.g., in a 4× reductionsystem, the reticle acceleration is four times the substrateacceleration), and (2) the design of the illumination system may be moredifficult compared to what is required for the sequence shown in FIGS.7A-7I.

FIGS. 9A-9I further illustrate another embodiment of how four siteslabeled 1-4 can be exposed using the exposure apparatus 410 asillustrated in FIG. 4 and as described above. Similar to the embodimentillustrated in FIGS. 7A-7I and 8A-8I, in this embodiment, the box withsolid lines is the first used field 962A, the box with dashed lines isthe second used field 962B, and the slashes represent the pattern beam.Further, the arrow again represents the direction in which the substrateis being moved during scanning at that particular time, with thesubstrate initially being moved down the page, then left, and then upduring the exposure of the four sites.

Starting with FIG. 9A, at the beginning of the exposure of the firstsite 1, the first pattern beam 936A (illustrated with slashes) isexposing the first site 1 and there is no second pattern beam. At thistime, the first used field 962A is positioned over the first site 1, andthe second used field 962B is not over any of the sites 1-4.

Next, referring to FIG. 9B, after the first site 1 is exposed, the firstused field 962A is positioned over the second site 2, and the secondused field 962B is positioned over the first site 1. At this timeneither of the pattern beams is being generated.

Subsequently, referring to FIG. 9C, once the second used field 962B ispositioned over the second site 2, the second pattern beam 936B(illustrated with slashes) begins to expose the second site 2, and thereis no first pattern beam.

Next, referring to FIG. 9D, while the second used field 962B is stillpositioned over the second site 2, the second pattern beam 936B(illustrated with slashes) continues to expose the second site 2, andthere is no first pattern beam.

Subsequently, upon the completion of the exposure of the second site 2,the substrate is moved to the left. Referring to FIG. 9E, once thesecond used field 962B is positioned over the third site 3, neither ofthe pattern beams is being generated.

Next, referring to FIG. 9F, once the first used field 962A is positionedover the third site 3, the first pattern beam 736A (illustrated withslashes) begins to expose the third site 3, and there is no secondpattern beam.

Subsequently, referring to FIG. 9G, while still exposing the third site3, the first used field 962A is positioned over the third site 3, andthe second used field 962B is positioned over the fourth site 4. At thistime both pattern beams 936A, 936B are being generated.

Next, referring to FIG. 9H, with the second used field 962B is stillpositioned over the fourth site 4, the second pattern beam 936B(illustrated with slashes) continues to expose the fourth site 4, andthere is no first pattern beam.

Subsequently, referring to FIG. 9I, after the second used field 962B isno longer positioned over the fourth site 4, and there is no patternbeam being generated.

With this sequence, the first site 1 and the third site 3 are exposedwith the first pattern beam 936A, and the second site 2 and the fourthsite 4 are exposed with the second pattern beam 936B. This sequenceprovides the same throughput and scanning distance as the sequenceillustrated in FIGS. 7A-7I, and requires some times (half as much) whenboth pattern beams are used simultaneously, like the sequence in FIGS.8A-8I. The advantage of this sequence is that the two masks are alwaysused for alternate exposures, so the requirement for mask accelerationis much lower. In other words, each of the mask stages 422A, 422B canperform its “turn-around” acceleration during an exposure using theother mask, 412B, 412A, respectively. For future machines with very highthroughput, this advantage may make this sequence the preferredembodiment.

It should be noted that with these designs, greater throughput of theexposure apparatus is achieved because the number of steps required toprocess the substrate is less than if the sites are scanned along thelong dimension of the sites.

FIGS. 10A-10D further illustrate one embodiment of how a first site 1can be exposed using the exposure apparatus 410 as illustrated in FIG. 4and as described above. Similar to the embodiments illustrated above, inthis embodiment, the box with solid lines represents the first usedfield 1062A, the box with dashed lines represents the second used field1062B, and the slashes represent the pattern beam. Further, the arrowagain represents the direction in which the substrate is being movedduring scanning at that particular time, with the substrate initiallybeing moved down the page, and then up during the exposure of the firstsite 1. Moreover, in this embodiment, the first site 1 is sequentiallyexposed to the first pattern beam 1036A and the second pattern beam1036B.

Starting with FIG. 10A, at the beginning of the exposure of the firstsite 1, the first pattern beam 1036A (illustrated with slashes) isexposing the first site 1 and there is no second pattern beam. At thistime, the first used field 1062A is positioned over the first site 1,and the second used field 1062B is not positioned over any of the sites.Further, at this time, the substrate is being moved down the page.

Next, referring to FIG. 10B, the first used field 1062A is nowpositioned over a second site 2 (i.e., not over the first site 1) andthe second used field 1062B is now positioned over the first site 1, andthe substrate is still being moved down the page. At this time, neitherof the pattern beams are being generated.

Subsequently, referring to FIG. 10C, the first used field 1062A is againpositioned over the second site 2 (i.e., not over the first site 1) andthe second used field 1062B is positioned over the uppermost portion ofthe first site 1. At this time, the substrate is beginning to be movedback up the page. With the second used field 1062B being positioned overthe uppermost portion of the second site 2, and the substrate beingmoved up the page, the second pattern beam 1036B is being generated andthe first site 1 is being exposed. Further, at this time, no firstpattern beam is being generated.

Next, referring to FIG. 10D, the first used field 1062A is positionedover the first site 1, and the second used field 1062B is not positionedover any of the sites. At this time, neither of the pattern beams arebeing generated.

Other sequences can be utilized than that illustrated in FIGS. 10A-10D.For example, two adjacent sites can be sequentially scanned in onemotion, then the substrate can be turned around and the second exposureof these sites can be performed. For example, while moving substrate inone direction along the X axis, the first site can be exposed using thefirst reticle and subsequently the second site can be exposed usingsecond reticle (similar as illustrated in FIGS. 9A-9D). Next, thedirection of the substrate along the X axis can be reversed, the secondsite can exposed using the first reticle, and subsequently the firstsite can be exposed using the second reticle. This is similar tosequence illustrated in FIG. 9A-9I, except without the Y directionstepping motion.

FIGS. 11A-11D further illustrate another embodiment of how a first site1 can be exposed using the exposure apparatus 410 as illustrated in FIG.4 and as described above. Similar to the embodiments illustrated above,in this embodiment, the box with solid lines is the first used field1162A, the box with dashed lines is the second used field 1162B, and theslashes represent the pattern beam. Further, the arrow again representsthe direction in which the substrate is being moved during scanning atthat particular time, with the substrate being moved down the pageduring the exposure of the first site 1. Moreover, in this embodiment,the first site 1 is exposed to both the first pattern beam 1136A and thesecond pattern beam 1136B.

Starting with FIG. 11A, at the beginning of the exposure of the firstsite 1, the first pattern beam 1136A (illustrated with slashes) isexposing the first site 1 and there is no second pattern beam. At thistime, the first used field 1162A is positioned over the first site 1,and the second used field 1162B is not positioned over any of the sites1-4.

Next, referring to FIG. 11B, both the first used field 1162A and thesecond used field 1162B are now positioned over the first site 1. Atthis time, both of the pattern beams 1136A, 1136B (illustrated withslashes) are being generated, and the first site 1 is simultaneouslybeing exposed to both the first pattern beam 1136A and the secondpattern beam 1136B.

Subsequently, referring to FIG. 11C, the first used field 1162A is nowpositioned over the second site 2 (i.e., not over the first site 1) andthe second used field 1162B is still positioned over the first site 1.At this time, the second pattern beam 1136B (illustrated with slashes)is exposing the first site 1 and no first pattern beam 1136A is beinggenerated.

Next, referring to FIG. 11D, both the first used field 1162A and thesecond used field 1162B are positioned over the second site 2 (i.e., notover the first site 1). At this time, neither of the pattern beams arebeing generated.

FIG. 12 is a schematic illustration of the first mask 412A, the secondmask 412B, the substrate 414, and one, non-exclusive embodiment of anoptical assembly 1220 having features of the present invention. As notedabove, the optical assembly 1220 projects and/or focuses the firstpattern beam 436A and the second pattern beam 436B onto the substrate414.

As illustrated, the optical assembly 1220 includes (i) the first opticalinlet 421A, (ii) the second optical inlet 421B, (iii) the optical outlet421C, (iv) a plurality of first vertical optical elements 1220AA thatare positioned along the first inlet axis, (v) a plurality of secondvertical optical elements 1220AB that are positioned along the secondinlet axis, (vi) a plurality of first transverse optical elements 1220ACthat are positioned along a first transverse axis between the firstinlet axis and the outlet axis, (vii) a plurality of second transverseoptical elements 1220AD that are positioned along a second transverseaxis between the second inlet axis and the outlet axis, and (viii) aplurality of third vertical optical elements 1220AE that are positionedalong the outlet axis.

During projection and/or focusing of the first pattern beam 436A fromthe first mask 412A onto the substrate 414, the first pattern beam 436Ais initially directed through the first optical inlet 421A and throughthe plurality of first vertical optical elements 1220AA. Subsequently,the first pattern beam 436A is redirected toward the plurality of firsttransverse optical elements 1220AC. Next, the first pattern beam 436A isredirected toward the plurality of third vertical optical elements1220AE. The third vertical optical elements 1220AE then project and/orfocus the first pattern beam 436A through the optical outlet 421C andtoward the substrate 421 offset from the outlet axis.

Similarly, during projection and/or focusing of the second pattern beam436B from the second mask 412B onto the substrate 414, the secondpattern beam 436B is initially directed through the second optical inlet421B and toward the plurality of second vertical optical elements1220AB. Subsequently, the second pattern beam 436B is redirected towardthe plurality of second transverse optical elements 1220AD. Next, thesecond pattern beam 436B is redirected toward the plurality of thirdvertical optical elements 1220AE. The third vertical optical elements1220AE then project and/or focus the second pattern beam 436B throughthe optical outlet 421C and toward the substrate 414 offset from theoutlet axis.

As illustrated in FIG. 12, the first vertical optical elements 1220AAare substantially identical to the second vertical optical elements1220AB. Additionally, the first transverse optical elements 1220AC aresubstantially identical to the second transverse optical elements1220AD. Accordingly, only the first vertical optical elements 1220AA andthe first transverse optical elements 1220AC will be described in detailherein. Further, both beams 436A, 436B travel through the same thirdvertical optical elements 1220AE.

The first vertical optical elements 1220AA include a plurality ofindividual optical elements labeled E1 through E18. In this embodiment,the first pattern beam 436A is altered and/or focused as it initiallypasses in a generally downward direction through optical elements E1through E13. Optical elements E1 through E13 are optical lenses that canbe made from material such as silicon dioxide (SiO₂). Subsequently, thefirst pattern beam 436A is reflected off optical element E14 so that itis now directed in a generally upward direction. In one embodiment,optical element E14 can be a spherical mirror. Next, the first patternbeam 436A is directed through optical elements E15 through E17. Asillustrated in FIG. 10, optical elements E15 through E17 are the same asoptical elements E11 through E13, with the first pattern beam 436Apassing through optical elements E11 through E13 in one direction andsubsequently passing through optical elements E15 through E17 and in thesubstantially opposite direction. Next, the first pattern beam 436A isreflected transversely off optical element E18 so that it is nowredirected toward the first transverse optical elements 1220AC. Opticalelement E18 can be a mirror or other reflecting element.

The first transverse optical elements 1220AC include a plurality ofindividual optical elements E19 through E29. The first pattern beam 436Ais altered and/or refocused as it passes in a generally transverse orhorizontal direction through optical elements E19 through E28. Opticalelements E19 through E28 are optical lenses that can be made frommaterial such as silicon dioxide (SiO₂). Subsequently, the first patternbeam 436A is reflected off optical element E29 so that it is nowredirected toward the third vertical optical elements 1120AE. In oneembodiment, optical element E29 can be a field splitting V-mirror.

The third vertical optical elements 1220AE include a plurality ofoptical elements E30 through E45. The first pattern beam 436A is alteredand/or refocused as it passes in a generally downward direction throughoptical elements E30 through E45. Optical elements E30 through E45 areoptical lenses that can be made from material such as silicon dioxide(SiO₂). The first pattern beam 436A then passes through element E46(represented as X's), which is a fluid, such as water, if the exposureapparatus 410 is an immersion type system, before being projected and/orfocused onto the substrate 414.

It should be noted that the design of the optical assembly 1220illustrated in FIG. 12 contains more intermediate images than theoptical assemblies used in prior art lithography machines. It should benoted that these intermediate images can be highly aberrated, as is thecase in this embodiment. This makes it easier to increase the field sizewithout increasing the diameter of the optical elements, since theoptical distance between the reticle and the wafer is much longer thanin the current state of the art for projection optical assemblies,thanks to the folded optical path (i.e. the physical distance betweenthe plane containing the reticle 412A and the plane containing thesubstrate 414 is nominally the same as current state of the art).Further, the optical assembly 1220 allows for the continuous exposure oftwo or more shots per scanning motion. With this exposure pattern, thereduction in scanning time is much greater than the increase in steppingtime, and dramatic improvements in throughput are possible.

Table 1, as provided below, illustrates one, non-exclusive example of aprescription for the optic elements E1 through E46 of the opticalassembly 1216 illustrated in FIG. 12. More particularly, for eachoptical element E1 through E46, the charts in Table 1 show aprescription for (i) the radius of curvature for the front of theoptical element, (ii) the radius of curvature for the back of theoptical element, (iii) the thickness of the optical element (in thecolumn for thickness the top number represents the distance between thatoptical element and the preceding optical element (or the mask in thecase of optical element E1), and the bottom number represents the actualthickness of that optical element, (iv) the aperture diameter for thefront of the optical element, and (v) the aperture diameter for the backof the optical element. The thickness of each optical element isspecified along the optical axis (e.g. the center of rotation for theelement).

TABLE 1 APERTURE ELEMENT RADIUS OF CURVATURE DIAMETER NUMBER FRONT BACKTHICKNESS FRONT BACK MASK INF 80.0000 E1 332.3631 CX −772.3579 CX38.0763 215.2012 217.2506 26.9220 E2 1988.1790 CX −557.1967 CX 26.6978220.9056 221.1825 56.1372 E3 128.4263 CX A(1) 31.0843 198.8483 187.853426.0025 E4 98.6558 CX 321.1966 CC 45.2849 159.9568 143.6474 16.3918 E5−454.4909 CC −730.0124 CX 59.99325 137.4985 118.9757 59.7289 E6 −64.8711CC −199.1701 CX 12.5000 125.5907 190.0548 1.0877 E7 −224.3732 CC−132.7050 CX 46.3257 196.0660 217.1116 1.0000 E8 A(2) −158.7960 CX45.6873 245.0434 260.0687 1.0000 E9 −646.1248 CC −226.2058 CX 51.0836289.0873 295.5915 1.0000 E10 360.6986 CX A(3) 53.3734 287.2861 282.7083139.9997 211.4006 100.0000 E11 237.9744 CX −1445.3266 CX 51.2169244.1453 240.7614 174.1733 E12 A(4) 487.4478 CC 12.5000 158.1046166.9962 58.1229 E13 −98.2161 CC −210.5104 CX 12.5000 168.7470 212.407624.2148 E14 −145.6557 CC −24.2148 218.4194 E15 −210.5104 CX −98.2161 CC−12.5000 209.9116 168.2949 −58.1229 E16 487.4478 CC A(5) −12.5000166.3525 155.5700 −174.1733 E17 −1445.3266 CX 237.9744 CX −51.2169252.3990 255.2359 −100.0000 DECENTER(1) E18 INF 0.0000 358.2570 230.1752139.9999 E19 A(6) −489.7915 CX 48.1053 269.5593 273.1352 1.0509 E20440.2750 CX −1319.4966 CX 42.3662 278.5086 276.5223 1.0004 E21 153.2021CX A(7) 35.3619 249.4052 236.0525 1.0048 E22 129.8182 CX 247.8748 CC51.0939 218.2553 199.2937 14.1804 E23 139.9820 CX 69.7240 CC 17.4815161.4679 118.1128 56.7295 E24 −317.8201 CC −19220.6836 CX 12.500092.5138 103.8677 51.6277 E25 −239.6328 CC −120.1306 CX 53.8056 186.4776208.1471 1.0000 E26 A(8) −134.3606 CX 57.5209 232.5554 249.2932 3.2068E27 3402.1195 CX −375.2978 CX 40.6273 270.0570 271.5381 9.9100 E28501.3345 CX −4078.3847 CX 31.4270 258.1145 253.6591 140.0003 DECENTER(2)E29 INF 0.0000 340.0505 167.4372 −119.0000 E30 −725.7800 CX 971.2181 CX−26.7346 215.7113 218.7057 −1.0000 E31 −246.2088 CX −2291.7420 CC−37.5566 227.3402 224.6272 −1.0000 E32 −240.3807 CX −491.2120 CC−27.0952 217.7132 211.0205 −1.0000 E33 −359.5177 CX A(9) −26.0330208.1157 200.6343 −2.5888 E34 3436.6049 CC −155.1981 CC −12.5000201.2703 181.4202 −53.9084 E35 201.2753 CC A(10) −12.5000 181.5783206.3011 −32.1960 E36 A(11) 22055.3033 CX −18.2557 222.3822 232.1830−5.7398 E37 −444.9630 CX 855.8885 CX −44.4071 269.0140 274.6713 −1.0250E38 −1241.2380 CX A(12) −48.8825 285.3656 288.3814 4.0469 E39 505.0198CC A(13) −19.5442 288.9709 293.2339 −27.7418 E40 A(14) 300.9422 CX−54.8835 293.3251 329.7481 −1.0029 E41 −384.4074 CX 1165.4799 CX−69.9286 356.7095 354.3822 −1.0000 347.3775 −1.0000 APERTURE STOP313.1895 E42 −192.8071 CX −336.3459 CC −57.1654 313.1895 301.4309−1.0015 E43 −146.6712 CX A(15) −63.7532 260.7714 240.3029 −1.2011 E44−93.7790 CX A(16) −53.0084 174.6861 139.7743 −1.0108 E45 −64.9508 CX INF−44.5062 105.4047 44.5875 E46 INF INF −1.5000 44.5875 36.2567 SUBSTRATEINF 36.2567

In Table 1, it should be noted that (i) positive radius indicates thecenter of curvature is to the right; (ii) negative radius indicates thecenter of curvature is to the left; (iii) dimensions are given inmillimeters; (iv) thickness is axial distance to next surface; and (v)image diameter is a paraxial value, it is not a ray traced value.

Table 2, as provided below, illustrates the calculation of asphericconstants related to the radius of curvature for certain of the opticalelements as shown in Table 1. More particularly, aspheric constant A(1)relates to the radius of curvature for the back of optical element E3;aspheric constant A(2) relates to the radius of curvature for the frontof optical element E8; aspheric constant A(3) relates to the radius ofcurvature for the back of optical element E10; aspheric constant A(4)relates to the radius of curvature for the front of optical element E12;aspheric constant A(5) relates to the radius of curvature for the backof optical element E16; aspheric constant A(6) relates to the radius ofcurvature for the front of optical element E19; aspheric constant A(7)relates to the radius of curvature for the back of optical element E21;aspheric constant A(8) relates to the radius of curvature for the frontof optical element E26; aspheric constant A(9) relates to the radius ofcurvature for the back of optical element E33; aspheric constant A(10)relates to the radius of curvature for the back of optical element E35;aspheric constant A(11) relates to the radius of curvature for the frontof optical element E36; aspheric constant A(12) relates to the radius ofcurvature for the back of optical element E38; aspheric constant A(13)relates to the radius of curvature for the back of optical element E39;aspheric constant A(14) relates to the radius of curvature for the frontof optical element E40; aspheric constant A(15) relates to the radius ofcurvature for the back of optical element E43; and aspheric constantA(16) relates to the radius of curvature for the back of optical elementE44.

Additionally, within the formula for the aspheric constants, Yrepresents the distance from the optical axis (i.e., the first inletaxis, a first transverse axis, or the outlet axis), CURV represents(1/radius of curvature), and K represents the conic constant.

TABLE 2 ASPHERIC CONSTANTS$Z = {\frac{({CURV})Y^{2}}{1 + \left( {1 - {\left( {1 + K} \right)({CURV})^{2}Y^{2}}} \right)^{1/2}} + {(A)Y^{4}} + {(B)Y^{6}} + {(C)Y^{8}} + {(D)Y^{10}} + {(E)Y^{12}} + {(F)Y^{14}} + {(G)Y^{16}} + {(H)Y^{18}} + {(J)Y^{20}}}$K A B C D ASPHERIC CURV E F G H J A(1) 0.00521230 0.000000 7.36515E−085.65704E−12 −1.19986E−15 3.47493E−20 1.94010E−24 −2.67446E−280.00000E+00 0.00000E+00 0.00000E+00 A(2) −0.00474024 0.0000001.94442E−08 7.19217E−13 −4.39422E−17 −8.49737E−22 1.08518E−25−2.62326E−30 0.00000E+00 0.00000E+00 0.00000E+00 A(3) −0.001819130.000000 1.97669E−08 −2.81921E−14 −2.03611E−18 3.92721E−23 8.64464E−29−2.01755E−32 0.00000E+00 0.00000E+00 0.00000E+00 A(4) −0.009439270.000000 4.03091E−07 −1.84915E−11 −3.06102E−16 −5.60022E−20 9.77410E−24−1.64771E−27 0.00000E+00 0.00000E+00 0.00000E+00 A(5) −0.009439270.000000 1.22035E−07 1.75899E−12 −8.89537E−18 2.56518E−20 −1.72833E−242.12380E−28 0.00000E+00 0.00000E+00 0.00000E+00 A(6) 0.00250445 0.000000−2.24797E−08 −1.71809E−14 4.18962E−18 −1.25992E−22 1.93598E−27−1.52571E−32 0.00000E+00 0.00000E+00 0.00000E+00 A(7) 0.005986170.000000 −1.78129E−08 −1.34754E−12 −9.63168E−18 −5.96286E−22 8.22593E−26−3.07075E−30 0.00000E+00 0.00000E+00 0.00000E+00 A(8) −0.004023850.000000 −5.66102E−08 4.94563E−13 −2.86196E−17 −1.14660E−21 6.70516E−26−1.34290E−30 0.00000E+00 0.00000E+00 0.00000E+00 A(9) 0.000432170.000000 −4.01551E−08 7.98475E−13 −8.77129E−17 −1.03388E−21 5.28663E−25−4.41691E−29 6.99988E−34 0.00000E+00 0.00000E+00 A(10) −0.007083340.000000 1.59565E−07 −5.12216E−12 3.09234E−16 −1.36558E−20 6.81623E−25−9.67188E−30 −7.26516E−35 0.00000E+00 0.00000E+00 A(11) −0.001596640.000000 8.79056E−08 −4.58660E−12 1.44100E−16 −1.79547E−20 4.80695E−25−2.72623E−29 1.93370E−33 0.00000E+00 0.00000E+00 A(12) 0.002622130.000000 1.87932E−08 7.71419E−13 −1.47309E−16 3.46140E−21 1.30616E−25−1.07939E−29 1.84542E−34 0.00000E+00 0.00000E+00 A(13) 0.003170500.000000 −2.49489E−08 −8.47598E−13 1.17616E−16 −3.41773E−21 −1.01449E−258.58972E−30 −1.27042E−34 0.00000E+00 0.00000E+00 A(14) 0.003958470.000000 6.54729E−09 3.01118E−13 1.06282E−17 −1.83601E−21 1.35202E−25−5.49884E−30 9.45241E−35 0.00000E+00 0.00000E+00 A(15) −0.003730590.000000 2.81186E−08 −3.40496E−12 1.73002E−16 −4.39804E−21 −1.60826E−251.48359E−29 −3.52669E−34 0.00000E+00 0.00000E+00 A(16) −0.005487810.000000 −1.89752E−07 −2.61284E−13 −1.75568E−15 2.78432E−20 2.85207E−23−8.14237E−27 5.98295E−31 0.00000E+00 0.00000E+00

Table 3, as provided below, illustrates the decentering information asit relates to optical elements E18 and E29 (i.e., certain of the mirrorelements). Table 3 further provides additional system characteristicsfor the optical assembly 1120.

TABLE 3 DECENTERING CONSTANTS DECENTER X Y Z ALPHA BETA GAMMA D (1)0.0000 0.0000 0.0000 −45.0000 0.0000 0.0000 (BEND) D (2) 0.0000 0.00000.0000 −45.0000 0.0000 0.0000 (BEND) A decenter defines a new coordinatesystem (displaced and/or rotated) in which subsequent surfaces aredefined. Surfaces following a decenter are aligned on the localmechanical axis (z-axis) of the new coordinate system. The newmechanical axis remains in use until changed by another decenter. Theorder in which displacements and tilts are applied on a given surface isspecified using different decenter types and these generate differentnew coordinate systems; those used here are explained below. Alpha,beta, and gamma are in degrees. DECENTERING CONSTANT KEY: TYPE TRAILINGCODE ORDER OF APPLICATION DECENTER DISPLACE (X, Y, Z) TILT (ALPHA, BETA,GAMMA) REFRACT AT SURFACE THICKNESS TO NEXT SURFACE DECENTER & BEND BENDDECENTER (X, Y, Z, ALPHA, BETA, GAMMA) REFLECT AT SURFACE BEND (ALPHA,BETA, GAMMA) THICKNESS TO NEXT SURFACE REFERENCE WAVELENGTH = 193.3 NMSPECTRAL REGION = 193.3-193.3 NM This is non-symmetric system. Ifelements with power are decentered or tilted, the first order propertiesare probably inadequate in describing the system characteristics.INFINITE CONJUGATES EFL = 8645.9595 BFL = 2159.9899 FFL = 23989.7701F/NO = 0.0000 AT USED CONJUGATES REDUCTION = −0.2500 FINITE F/NO =−0.3704 OBJECT DIST = 80.0000 TOTAL TRACK = 763.7529 IMAGE DIST =−1.5000 OAL = 685.2529 PARAXIAL IMAGE HT = 18.1250 IMAGE DIST = −1.5000SEMI-FIELD ANGLE = 0.0000 ENTR PUPIL DIAMETER = 0.717E+10 DISTANCE =0.100E+11 EXIT PUPIL DIAMETER = 4314.9615 DISTANCE = 2159.9951 NOTES FFLis measured from the first surface BFL is measured from the last surface

It should be noted that the projection optical assembly 1216 providedherein is uniquely designed so that a plurality of intermediate imagesare directed at the field splitting V-mirror E-29 inside the projectionoptical assembly 1216. Stated in another fashion, with the presentdesign, the field splitting V-mirror E-29 is positioned away from theimage plane of the optical assembly 1216. As used herein, the term“image plane” shall mean the plane in which an image produced by theoptical assembly is formed. With the present design, the image plane ofthe optical assembly 1216 is located at the substrate. Thus, in FIG. 12,elements E-30 through E-46 separate the field splitting V-mirror E-29from the image plane. With the present design, many aberrated images aretransmitted through elements E-30-E-46. The aberrated images give theoptical designer much more flexibility in balancing aberrations beforeand after the V-mirror E-29. This also enables the larger field size forscanning along the short dimension of the site (X axis scan), without alarger and more complicated optical design.

Additionally, in the embodiment illustrated in FIG. 12, the projectionoptical assembly 1216 is a Catadioptric design that includes one or morelenses and one or more curved mirrors. In this embodiment, theprojection optical assembly 1216 includes at least one concave mirror(e.g. E14 for each optical path), for the purposes of field curvaturecorrection over the large field size of 33 mm. It is conceivable thatthe projection optical assembly 1216 can be designed with more than onecurved mirror per optical path.

Further with the projection optical assembly 1216 provided herein, thefold mirror E18 allows light to be incident on, and reflected from, theconcave mirror E14 without obscuration. The fold direction is in theshort direction of the field (e.g. 5 mm at the wafer), and it is closeto a second intermediate image (FIG. 12 illustrates the rays coming to afocus right next to E18, as they do next to E29). This facilitates thefolding arrangement at E18, in the same way that it does at the V-mirrorE29.

Additionally, it should be noted that the projection optical assembly1216 illustrated and described herein is a 4× reduction system thatreduces the size of the projected image between elements E1 and E45.Alternatively, the projection optical assembly 1216 can be designed tobe a 1× system, a magnification system, or a reduction system that isgreater than or less than 4×.

FIG. 13 is a simplified perspective view that includes, a first mask1312A, a second mask 1312B, a third mask 1312C, a fourth mask 1312D, andanother embodiment of an optical assembly 1320. In this embodiment, theoptical assembly 1320 projects and/or focuses a first pattern beam 1336Afrom the first mask 1312A, a second pattern beam 1336B from the secondmask 1312B, a third pattern beam 1336C from the third mask 1312C, and afourth pattern beam 1336D from the fourth mask 1312D onto the substrate1414 (illustrated in FIG. 14).

In this embodiment, the masks 1312A-1312D can be individually positionedand individually illuminated, and the substrate can be positioned withcomponents that somewhat similar to those described above andillustrated in FIG. 4. As provided herein, the mask patterns from thefour masks 1312A-1312D can be sequentially transferred to the substrate414 while the substrate 14 is being moved along the X axis (e.g. thescanning along the short dimension of the site) to provide furtherimprovements in the throughput of the system.

One embodiment of a four mask exposure apparatus is disclosed inconcurrently filed application Ser. No. ______, entitled “OpticalImaging System and Method for Imaging Up to Four Reticles to a SingleImaging Location” (PAO1041-00/045004/Oremland Ref. No. 6162.118US),which is assigned to the assignee of the present invention, and isincorporated by reference herein.

The design of the optical assembly 1320 can be varied depending on therequirements of the exposure apparatus. As illustrated, the opticalassembly 1320 is substantially similar to the optical assembly 1220illustrated in FIG. 12. For example, the design, positioning andorientation of optical elements E6 through E46 (the immersion fluid isnot shown in FIG. 13) is substantially repeated in this embodiment.Accordingly, a detailed description that portion of the optical assembly1320 will not be repeated herein. However, the optical assembly 1320, asillustrated in the embodiment shown in FIG. 13, includes (i) opticalelements E1 through E5, which are positioned substantially between thefirst mask 1312A and optical element E6 and are oriented substantiallytransversely relative to optical element E6, (ii) optical elements E1′through E5′, which are positioned substantially between the second mask1312B and optical element E6 and are oriented substantially transverselyrelative to optical element E6, (iii) optical elements E1″ through E5″,which are positioned substantially between the third mask 1312C andoptical element E6″ and are oriented substantially transversely relativeto optical element E6″, and (iv) optical elements E1′″ through E5′″,which are positioned substantially between the fourth mask 1312D andoptical element E6″ and are oriented substantially transversely relativeto optical element E6″.

Additionally, the optical assembly 1320 further includes a firstswitching mirror 1384A that is positioned substantially between opticalelements E5 and E6 and between optical elements E5′ and E6, and a secondswitching mirror 1384B that is positioned substantially between opticalelements E5″ and E6″ and between optical elements E5′″ and E6″ on theopposite side of the optical assembly 1320. The first switching mirror1384A enables the optical assembly 1320 to selectively, alternativelyand/or sequentially project and/or focus the first pattern beam 1336Afrom the first mask 1312A onto the substrate 414, and the second patternbeam 1336B from the second mask 1312B onto the substrate 414. Similarly,the second switching mirror 1384B enables the optical assembly 1320 toselectively, alternatively and/or sequentially project and/or focus thethird pattern beam 1336C from the third mask 1312C onto the substrate414, and the fourth pattern beam 1336D from the fourth mask 1312D ontothe substrate 414.

The process of the optical assembly 1320 projecting and/or focusing thefirst pattern beam 1336A from the first mask 1312A onto the substrate414 is substantially similar to the projecting and/or focusing of thesecond pattern beam 1336B from the second mask 1312B, the third patternbeam 1336C from the third mask 1312C, and/or the fourth pattern beam1336D from the fourth mask 1312D onto the substrate 414.

FIG. 14 is a simplified top view of one non-exclusive embodiment of asubstrate 1414 that was exposed utilizing the four mask design and theoptical assembly 1320 illustrated in FIG. 13. The design of thesubstrate 1414 is similar to the substrate 414 described above andillustrated in FIG. 5A. However, in FIG. 14, the sequence in which thesites 1415 are exposed is different.

In this embodiment, the substrate 1414 is again labeled “1” through “32”(one through thirty-two). In this example, the labels “1” through “32”represent one non-exclusive embodiment of the sequence in which maskpatterns from each of the first mask 1312A, the second mask 1312B, thethird mask 1312C and the fourth mask 1312D (illustrated In FIG. 13) canbe transferred to the sites 1415 on the substrate 1414.

Moreover, FIG. 14 includes an exposure pattern 1452A (illustrated with adashed line) which further illustrates the order in which the maskpatterns are transferred to sites 1415. In this example, the exposurepattern 1452A comprises a plurality of scanning operations 1452B and aplurality of stepping operations 1452C, wherein the scanning operations1452B and the stepping operations 1452C alternate so that the exposureproceeds in a scan-step-scan-step-scan fashion. In this embodiment, thescanning 1452B occurs as the substrate 1414 is moved along a scan axis1458 (the X axis), and the stepping 1452C occurs as the substrate 1414is moved along a step axis 1460 (the Y axis).

It should be noted that in this embodiment, the sites are scanned alongthe short dimension of the sites. This allows for greater throughput ofthe exposure apparatus because there are fewer steps of the substrate1414 required during the exposure of the substrate 1414.

In this embodiment, because four individual masks 1312A, 1312B, 1312C,1312D are utilized, four adjacent sites 1415 (e.g. 1, 2, 3 and 4) can bescanned sequentially while moving the substrate 1414 at a constantvelocity along the scan axis 1458. As a result thereof, the substrate1414 does not have to be stepped and reversed in direction between theexposures of adjacent sites 1415. Instead, for the embodimentillustrated in FIG. 13, the substrate 1414 is only stepped between theexposure of sets of four adjacent sites 1415 aligned on the scan axis1458. Stated in another fashion, with the present design, there is onestepping motion for every four sites 1415 scanned. This results in fewersteps and significantly improved throughput from the exposure apparatus410 (illustrated in FIG. 4).

It should be noted that in this example, the site 1415 that is exposedfirst and the order in which the sites 1415 are exposed can be differentthan that illustrated in FIG. 14. Further, the site 1415 that is firstexposed can be located away from the edge of the substrate 1414.

Semiconductor devices can be fabricated using the above describedsystems, by the process shown generally in FIG. 15A. In step 1501 thedevice's function and performance characteristics are designed. Next, instep 1502, a mask (reticle) having a pattern is designed according tothe previous designing step, and in a parallel step 1503 a wafer is madefrom a silicon material. The mask pattern designed in step 1502 isexposed onto the wafer from step 1503 in step 1504 by a photolithographysystem described hereinabove in accordance with the present invention.In step 1505, the semiconductor device is assembled (including thedicing process, bonding process and packaging process), finally, thedevice is then inspected in step 1506.

FIG. 15B illustrates a detailed flowchart example of the above-mentionedstep 1504 in the case of fabricating semiconductor devices. In FIG. 15B,in step 1511 (oxidation step), the wafer surface is oxidized. In step1512 (CVD step), an insulation film is formed on the wafer surface. Instep 1513 (electrode formation step), electrodes are formed on the waferby vapor deposition. In step 1514 (ion implantation step), ions areimplanted in the wafer. The above mentioned steps 1511-1514 form thepreprocessing steps for wafers during wafer processing, and selection ismade at each step according to processing requirements.

At each stage of wafer processing, when the above-mentionedpreprocessing steps have been completed, the following post-processingsteps are implemented. During post-processing, first, in step 1515(photoresist formation step), photoresist is applied to a wafer. Next,in step 1516 (exposure step), the above-mentioned exposure device isused to transfer the circuit pattern of a mask (reticle) to a wafer.Then in step 1517 (developing step), the exposed wafer is developed, andin step 1518 (etching step), parts other than residual photoresist(exposed material surface) are removed by etching. In step 1518(photoresist removal step), unnecessary photoresist remaining afteretching is removed. Multiple circuit patterns are formed by repetitionof these preprocessing and post-processing steps.

It is to be understood that the exposure apparatuses 10 disclosed hereinare merely illustrative of the presently preferred embodiments of theinvention and that no limitations are intended to the details ofconstruction or design herein shown other than as described in theappended claims.

1. An exposure apparatus for transferring a first mask pattern to asubstrate, the substrate including a first site having a first sitedimension along a first axis and a second site dimension along a secondaxis that is perpendicular to the first axis, wherein the second sitedimension is larger than the first site dimension, the exposureapparatus comprising: an illumination system that generates a firstillumination beam that is used to generate a first pattern beam thatcontains the first mask pattern; a substrate stage assembly that retainsand positions the substrate along the first axis; and a control systemthat controls the illumination system, and the substrate stage assemblyso that the first mask pattern is transferred to the first site whilethe substrate stage assembly is moving the substrate along the firstaxis.
 2. The exposure apparatus of claim 1 further comprising aprojection optical assembly that focuses the first pattern beam on thesubstrate; wherein the projection optical assembly includes a used fieldhaving a first field dimension along the first axis and a second fielddimension along the second axis, wherein the first field dimension issmaller than the second field dimension.
 3. The exposure apparatus ofclaim 2 wherein the first field dimension is shorter than the first sitedimension and the second field dimension is equal to or greater than thesecond site dimension.
 4. The exposure apparatus of claim 1 furthercomprising a first mask that includes the first mask pattern and a firstmask stage assembly that retains and positions the first mask along thefirst axis relative to the first illumination beam, wherein the firstpattern beam is created by directing the first illumination beam at thefirst mask pattern, and wherein the control system controls the firstmask stage assembly so that the first mask stage assembly is moving thefirst mask along the first axis while the first mask pattern is beingtransferred to the first site.
 5. The exposure apparatus of claim 4further comprising a second mask stage assembly that retains andpositions a second mask, wherein the illumination system generates asecond illumination beam that is directed at the second mask, whereinthe second illumination beam illuminates a second mask pattern of thesecond mask to generate a second pattern beam, and wherein the opticalassembly focuses the first pattern beam and the second pattern beam onthe substrate.
 6. The exposure apparatus of claim 5 wherein thesubstrate further includes a second site, and wherein the control systemcontrols the illumination system, the mask stage assemblies and thesubstrate stage assembly to transfer an image of the first mask patternto the first site, and an image of the second mask pattern to the secondsite.
 7. The exposure apparatus of claim 6 wherein the control systemcontrols the substrate stage assembly to continuously move the substratealong the first axis when transferring the images to the first site andthe second site.
 8. The exposure apparatus of claim 7 wherein thecontrol system controls the substrate stage assembly to move thesubstrate a movement step along the second axis after the second maskpattern is transferred to the second site.
 9. The exposure apparatus ofclaim 4 wherein the control system controls the illumination system, thefirst mask stage assembly and the substrate stage assembly so that theentire first mask pattern is transferred to the first site while thefirst mask stage assembly is moving the first mask along the first axis,and the substrate stage assembly is moving the substrate along the firstaxis.
 10. The exposure apparatus of claim 1 wherein the control systemcontrols the substrate stage assembly to move the substrate a movementstep along the second axis after the first mask pattern is transferredto the first site.
 11. A process for manufacturing a wafer that includesthe steps of providing a substrate having a first site and a secondsite, and transferring the first mask pattern to the first site and thesecond site of the substrate with the exposure apparatus of claim
 1. 12.A method for transferring a first mask pattern to a substrate, thesubstrate including a first site having a first site dimension along afirst axis and a second site dimension along a second axis that isperpendicular to the first axis, wherein the second site dimension islarger than the first site dimension, the method comprising the stepsof: directing a first pattern beam that contains the first mask patternat the substrate; positioning the substrate along the first axis with asubstrate stage assembly; and controlling the illumination system, andthe substrate stage assembly with a control system so that the firstmask pattern is transferred to the first site while the substrate stageassembly is moving the substrate along the first axis.
 13. The method ofclaim 12 wherein the step of directing includes the steps ofilluminating the first mask pattern with a first illumination beam froman illumination system to generate the first pattern beam, and focusingthe first pattern beam on the substrate with an optical assembly. 14.The method of claim 13 wherein the step of focusing includes the opticalassembly including a used field having a first field dimension along thefirst axis and a second field dimension along the second axis, whereinthe first field dimension is smaller than the second field dimension.15. The method of claim 14 wherein the step of focusing includes thefirst field dimension being shorter than the first site dimension andthe second field dimension being equal to or greater than the secondsite dimension.
 16. The method of claim 13 further comprising the stepsof positioning a second mask with a second mask stage assembly,generating a second illumination beam that is directed at the secondmask with the illumination system, illuminating a second mask pattern ofthe second mask with the second illumination beam to generate a secondpattern beam, and focusing the first pattern beam and the second patternbeam on the substrate with the optical assembly.
 17. The method of claim16 wherein the substrate further includes a second site, and wherein thestep of controlling includes the step of controlling the illuminationsystem, the mask stage assemblies and the substrate stage assembly withthe control system so that an image of the first mask pattern istransferred to the first site, and an image of the second mask patternis transferred to the second site.
 18. The method of claim 17 whereinthe step of controlling includes the step of controlling the substratestage assembly with the control system to continuously move thesubstrate along the first axis when transferring the images to the firstsite and the second site.
 19. The method of claim 17 further comprisingthe step of moving the substrate a movement step along the second axisafter the second mask pattern is transferred to the second site.
 20. Themethod of claim 12 wherein the step of controlling includes the step ofcontrolling the illumination system, and the substrate stage assemblywith the control system so that the entire first mask pattern istransferred to the first site while the substrate stage assembly ismoving the substrate along the first axis.
 21. The method of claim 1 2further comprising the step of controlling the substrate stage assemblywith the control system to move the substrate a movement step along thesecond axis after the first mask pattern is transferred to the firstsite.